Gear Review: Simtek Duo Wireless Security Sensor (Production Model)

Gear Review: Simtek Duo Wireless Security Sensor (Production Model)

Jeremy S. for TTAG

Last February I reviewed a prototype Simtek Duo, and loved it. Well, production versions have been shipping for a couple months now and it seemed like a good idea to follow up and review one, since this is what customers are actually receiving. Plus there have been a handful of updates and refinements along the way.

Gear Review: Simtek Duo Wireless Security Sensor (Production Model)

Jeremy S. for TTAG

Little has changed with the sensor itself. Each Simtek Duo has both a motion sensor and a light sensor. A trigger event for either one or both will send an alert out over the cell phone network to you and/or other people of your choosing.

Jeremy S. for TTAG

That alert can be a text message.

Gear Review: Simtek Duo Wireless Security Sensor (Production Model)

Jeremy S. for TTAG

Or a text message plus a push notification.

Jeremy S. for TTAG

In the mobile app settings the owner can change their device’s name, the alert message that’s sent, who’s subscribed to the notifications (requires their approval), and whether or not to enable those push notifications.

Gear Review: Simtek Duo Wireless Security Sensor (Production Model)

Jeremy S. for TTAG

Syncing a Duo to your phone is extremely easy. Simply open up the app, choose to add a new device (which is the first and only option if your app doesn’t already have any registered devices), and scan the QR code on the bottom of the device. The app automatically ingests the serial number and other information. Plug in your cell phone number, enter the PIN code that’s texted to you, and you’re done.

Gear Review: Simtek Duo Wireless Security Sensor (Production Model)

Jeremy S. for TTAG

A SIM card is pre-installed in each Duo. It’ll connect to any GSM mobile network in 200+ countries, and the device automatically chooses the network with the strongest signal.

Yes, this means a cellular messaging plan is required. Thankfully, Simtek makes this easy. You pay them a monthly ($4) or annual ($43) fee, and they take care of the charges from the cellular providers. If you’re traveling around domestically or internationally, there’s no worry about changing plans or anything like that. It just works. Though, if you were so inclined, I do believe you could use your own SIM card.

While only the weakest of cell signals is necessary — the Duo just has to squeak out a simple SMS message — the included, extended antenna can help in circumstances where coverage is poor and/or the unit is buried inside something. You know, like a steel gun safe. The antenna has a magnetic base and the cord can be run through a hole in the safe with the Duo on the inside and the antenna stuck on the outside. Though in 98% of cases, there’s a sufficient signal even with everything inside of a safe that the Duo works perfectly.

Gear Review: Simtek Duo Wireless Security Sensor (Production Model)

Jeremy S. for TTAG

On another of the Duo’s three sides, LEDs show when the device is detecting an infrared motion signature as well as when the device is triggered and an alert is successfully sent.

Gear Review: Simtek Duo Wireless Security Sensor (Production Model)

Jeremy S. for TTAG

The unit’s third side contains a micro USB port for charging the internal CR123A battery (which is included). It’s expected to last about a year between charges with an average of 10 alerts per month.

Gear Review: Simtek Duo Wireless Security Sensor (Production Model)

Jeremy S. for TTAG

Clicking on the app push notification takes you to the alert history page within the app. There you can see current stats of your Duo such as battery charge state and cell network signal strength. Below that will be a log of all your Duo’s trigger events.

If you then select one of the trigger events, a map opens up. It includes the cell phone triangulation-based location of your device at the time of the alert, shown both on a map and via longitude and latitude coordinates. Cell network-based location can vary in accuracy, but suffice it to say that I haven’t included a screen shot of this on my app because it dropped that map pin precisely where my house is on the displayed street map.

By using the cell network instead of WiFi, Simtek has created a device that works almost anywhere in the world and is far less susceptible to power outages (intentional or otherwise), internet outages, hacking, etc. It’s also more easily portable without the owner having to continuously, manually connect to new networks.

Gear Review: Simtek Duo Wireless Security Sensor (Production Model)

Jeremy S. for TTAG

My Duo lives on the pile of crap on top of my safe. While one interesting hack of the unit is to turn it into a motion sensor-only affair by putting black electrical tape over the light sensor — this can be handy to monitor spaces like inside your sailboat, RV, car, or open-to-daylight shed or warehouse should someone break in while you’re away — I didn’t have to do this for my particular safe setup.

Gear Review: Simtek Duo Wireless Security Sensor (Production Model)

Jeremy S. for TTAG

Because I built my SnapSafe Super Titan XL inside of my office closet (then buried it in crap). Close the door and the Simtek Duo arms itself within a couple of seconds. Open the door, and either the light sensor or motion sensor alerts first.

I figure why wait until the safe is opened to get an alert? With this setup, my phone is pinging away within 20 seconds of the Duo triggering, and whoever’s rifling through my stuff just ran out of time to work on the safe.

By employing either motion-only or motion and light warnings, a Simtek Duo owner can alarm a suitcase, hotel safe, vehicle trunk or glove box, cookie jar, nightstand drawer, coffin, storage unit / shed / warehouse, refrigerator, home or some flavor of mobile home, vehicle interior, dungeon, closet, room, bunker, humidor, wife’s wallet, alcohol cabinet or cellar, mailbox, biblical ark, garage, sweat lodge, or any other “off-limits” space.

The Simtek Duo is about as simple a security system as can be and as reliable as can be, and that’s a fantastic combination. It gives me additional peace of mind when I’m away from home.

Specifications: Simtek Duo Wireless Security Sensor

Dimensions: 1.48″ x 3.66″ x 3.26′
Weight: 4.3 oz
Material: ABS plastic
Colors: black, camouflage, or white
Battery Life: up to 1 year
Sensors: visible light and passive infrared motion sensor
Sensitivity: any visible light or 15′ by 15′ motion detection range
Connectivity: cellular (GSM)
Battery Type: rechargeable lithium ion CR123a
Warranty: 1 year limited with free tech support
MSRP: $200 (currently on sale for $150) plus either $4 per month or $43 per year for mobile data plan

Ratings (out of five stars):

Overall * * * * *
The Duo does exactly what it says it will and it’s simple and reliable as can be. Now that the MSRP is half of what it was during prototype phase and it looks like the going rate may be more like $150-ish, I’m happy to give the Duo a full five stars. It’s a great device with all sorts of potential and valuable uses.


  1. avatar Hippi says:

    So how easy is it to block the signal?, most of the major flaws in the vehicle GPS systems(LoJack etc…) Is that the outgoing signal is easily blocked or jammed preventing it to send an alert before tripping it.

    1. avatar GS650G says:

      Low jack can be defeated by driving the car into a metal container. Safes don’t have tires and engines.

      1. avatar Yepnope says:

        You guys watch too many movies

        1. avatar Jeremy S. says:


          Yeah I gotta say, if you’re getting hit by a heist crew that’s knocking out power and jamming WiFi and cell phone signals, you’ve either done something really wrong or really right. I’m FAR from attracting that kind of special attention haha

    2. @Hippi it is not easy to block the signal as it uses a penta band cellular modem that connects to different networks automatically. It also uses 2 factor authentication and all transmissions are sent over an encrypted connection.

      1. avatar Hippi says:

        Thanks for the answer hi tec thieves suck I know. A pair got to the closest gas station (about seven miles) with dads 32(GPS tracker installed) lucky local cops knew him and the car. Cops found a blocker in the car.

  2. avatar GS650G says:

    One method pings a cell tower randomly as a keep alive heartbeat so the signal is not easily identified. If the signal is a mystery it’s hard to block without causing a widespread outage that would get noticed.
    And if it’s not continuously transmitting a their would know it’s there unless someone blabbed.
    Security takes many forms and OPSEC applied to all.of them.

    The fact it can search for different towers or carriers is a plus as you would need to jack more than one to blind it.

    Now if it can trigger mustard gas in the room that would be a plus.

    1. avatar Jeremy S. says:

      After initializing, it only sends out a signal when it’s triggered and sends an alert. It’s otherwise completely passive.

  3. avatar Tom in Oregon says:

    Why not WiFi only? Or did I miss that speed reading…

    I really miss the auto fill feature for my name and email.

    1. avatar Jeremy S. says:

      Missed it speed reading 😉 …I shall quote myself (always an “author’s” favorite thing to do!):

      By using the cell network instead of WiFi, Simtek has created a device that works almost anywhere in the world and is far less susceptible to power outages (intentional or otherwise), internet outages, hacking, etc. It’s also more easily portable without the owner having to continuously, manually connect to new networks.

      1. avatar little horn says:

        don’t care. i am not adding another bill. wifi or bust.

  4. avatar GS650G says:

    Wi-Fi is dependent on other systems and can be sniffed for devices. It’s a network device. Cellular is more secure and can use different carriers. Like having several networks instead of one.
    Wi-Fi can be cut outside the house by snipping the line going in. It can also be DDoS attacked from outside.

    1. GS650G well said regarding wifi. The other big drawback to WIFI was that we found it hard to get signal out of the safe on the wifi frequency spectrum, andoften times the router was no where near where our safe was stored. Additionally, the sensor would be the last password you’d remember to change if you got a new router and with all of the outages we experience with Comcast on a monthly basis, felt that it was just too unreliable and insecure to do it. We may offer wifi in the future but didn’t want to compromise on this one.

      The other awesome bonus feature with cellular is that we have location triangulation – so if someone walks off with your safe, you can get a rough vicinity location of where it might be at when they open the safe up across town!

  5. avatar Yepnope says:

    Im glad you said “wife’s wallet”…by far the most practical application

    1. avatar Jeremy S. says:

      I was partial to “coffin.” But, yeah, my wife thought the “wife’s wallet” one was so hilarious I still have the bruise.

  6. avatar Joe in San Antonio says:

    Looks like the solution that I have been looking for, is there a way to get dual sensors to cover my house when I am away?

    1. @Joe in San Antionio

      You can pick up more than one sensor – we’d be happy to provide a $50 off coupon if you email [email protected] for more than one. Note, they are best used in places where there is not frequent traffic – like your safe, an off limits closet or drawer etc – and not something like a front door or garage where you will be getting lots of notifications, as they won’t be very valuable. You want to deploy the Simtek sensor in any area where getting alerts means something is actually happening. Combined with in home surveillance cameras and other alarm systems they can significantly enhance your awareness and defense nets. Check it out at

      1. Here’s the $50 off two sensors discount code a few people have asked for:


        Use ^ this code during checkout if you’re interested. Will also get you free shipping.

    2. avatar Jeremy S. says:

      Yes you can sync any number of sensors to the same app, and give them unique names (e.g. gun safe, bedroom, sex dungeon, shoe box full of drugs, etc.) so you know which sensor is alerting.

  7. avatar possum the red nose delete says:

    Simply open up the app and open up your privacy. Cell phones are Big Brothers face behind the Television.

    1. avatar Jeremy S. says:

      Tiny violin for you, sir.

      FYI, the Simtek app requires zero access permissions if you want to input your device’s ID manually and only access to use your phone’s camera if you want to ingest the ID automatically from the QR code (a permission that you can rescind afterwards). Most apps demand access to all sorts of capabilities and data in order to use them. The Simtek app requires none and requests only one.

  8. avatar impaired hearing says:

    looks good. maybe a future version could have a camera on it so it take pictures of whoever/whatever sets it off?

    1. avatar Rusty Chains says:

      A cheap Wyse camera off Amazon will do that for you, but it needs WiFi to send you data. SMS is why this is cheap to run at less than I pay for a month cell service for a year.

  9. avatar Felix says:

    Who does it send the SMS message to — my own phone number, or the Simtek HQ number? Unless there is some sort of configuration, either before it ships or when I first connect to it, it would probably be Simtek HQ, which means they have to look up my account based on a serial number in the message, then send me a separate message. I realize that allows the app to connect to HQ and report statistics, triangulation location, etc, but it also means if Simtek ever drops the business, all sold Duos become instant paperweights.

    Or maybe it sends two SMS messages, one to my phone and one to HQ. That would be nice.

    I didn’t see any downloadable manual on the website. That would be nice too.

    1. Hey Felix – In the event Simtek were to go belly up as you mention – the sensors are easily reprogrammed to bypass our server and could send directly to the users phone number. So they should never be a paper-weight. Each sensor has top of the line hardware that will last for many many years. We’ve had people using them without issue for almost 2 years so far, and look forward to many more! Check out the setup guide at the footer of our website that should give you more info, as well as the footer of our website which has the FAQ section.

      1. avatar Felix says:

        I did order one. I didn’t see any PDFs of the user manual.

        Good to know it is future proofed in being able to text me directly.

        About the only thing I have thought of as an improvement is some way to not alert when I open the safe or suitcase or coffin, say some PIN I could enter in the dark before turning the lights on. But that would add expense, not be very practical, and open up a huge security hole. And the false alarms send the text to me, not the police, so there’s no real need to avoid them.

        I’ve also been thinking of other uses for these, like hanging one on the front door at night or putting under a car seat. So there’s another question — if I did buy several of them, all for the same account, could they all get by on the same SMS subscription of $4/month or $43/year?

  10. avatar Tex Pat says:

    If someone goes in my office (where the safe is), the motion sensor of my security system is going to fire off. I will immediately get a text and they will notify the police.

    This product seems stupid.

    1. avatar Jeremy S. says:

      I was going to make some jokes about alarming coffins and such, but seriously let’s not forget how completely portable this unit is and how many dozens of things you could use it for. If you have a home security system then you obviously don’t require additional systems serving that same function. But maybe you still want to alarm a specific closet or drawer or the trunk of your car or a storage unit or whatever the heck ever whether you’re in your home with your security system turned off or not. Come on, man, have *some* minimum level of creativity above naught.

    2. avatar Jeremy S. says:

      And, I’m sorry, but are you seriously calling a product stupid that serves the same purpose as a different product that you choose to pay money for? This is hard for me to reconcile. Next you’ll tell us that coolers are a stupid product because you already own a refrigerator.

      1. avatar Tex Pat says:

        I was probably unduly harsh in my initial post.

        1) Used in a home (as in the review) or office setting, I think that there is a very small market for the product. Most people, who have security concerns, would be better served with a more robust security system. Thus, the size of the potential home/office market is probably very small.

        2) After additional thought, I do see a use for mobile users (sheds, trailers, etc).

  11. avatar Anon says:

    Tex Pat,
    Not stupid. They do what everybody does. For $48 per year. Another F#€^^%G toll gate.

    1. Anon

      Thanks for the laugh/

      Optional to use our dataplan (you can use your own GSM simcard, not recommended since it won’t be global or have triangulation capabilities). We looked at wifi, and found it to be a poor option for safes and for deploying out in the field (range, hotel, etc.) It was too easily defeated by cutting power, manually connecting to networks and frequent outages. Plus, most people don’t have great wifi signal coverage where the safe is and definitely not in places like their glovebox in their truck etc..

      $4 per month is less than a cup of coffee for reliable alerts anywhere in the world + location triangulation. Don’t like it don’t buy it. We do have a 30 day refund policy and stand behind the product we engineered for over 2 years. The experience is very different than other products on the market.

  12. avatar Sora says:

    Liberty Safe-Alert (made by another company and rebadged) sends out via wifi of home internet to text message AND emails. $100 last I check and NO Fees.
    Another alternative to check.
    It scans moisture, heat, light, motion. Very sensitive to motion and light.
    But I think moisture probably needs an add-on that’s not offered in USA.

    1. avatar Felix says:

      WiFi is not nearly as portable or universal, and takes more power. For a static setup, it is better. But this thing is not meant for static situations.

    2. avatar Brady says:

      Those liberty safe elertus are $200 everywhere, and not as versatile. As Felix mentioned they are for only static situations and read some of the reviews the problem as it relies on WiFi which everyone’s goes out at some point, or worse someone could simply unplug the router in the family room and it’s done. We wanted to do one thing well and reliably.

  13. avatar Joe says:

    You can’t charge a cr123a battery. They are a primary battery.

    1. avatar Brady says:

      Uses rcr123a – the rechargeable version. Can be recharged simply by plugging in the included micro usb cable to the sensor, and the device will last up to a year on 10 alerts per month.

    2. avatar Jeremy S. says:

      I guess we shouldn’t tell that to the 849 listings for rechargeable ones on Amazon, then, eh?

  14. avatar Old Guy in Montana says:

    A bit disappointed so far…

    Ordered one on the 8th…still waiting. Checked status it is en route from a plant in China through Hong Kong through US Customs into the US Mail system shuffling around a good part of the US and destined to be delivered sometime in the next few days…call it two weeks to get one sent to your home.

    A few observations:

    First: The site and order response e-mail did not mention that it would take weeks to ship one from China (wonder if the SIM card routes through Chinese Army servers?).

    Second: I have an older Android smart phone…it is incompatible with the system (didn’t find this out until well after I ordered) this connection information should be prominently displayed on the site.

    Third: Did I mention that I received an invitation from Simtek a few days ago to recommend the product to others on a referral program (bloody hell, I don’t even have the device yet).

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