This is the fourth wallet finder/tracker that I stumbled on by mistake. For whatever reason, when I search on Amazon, this thing never came up. Eventually, some targeted ads on Facebook recommended the Ekster to me, so I decided to look into it, because my experiences with the Innway and Orbit cards were a bust. I was about to go with the Tile, but fortunately I discovered this before I purchased it.I will start off with the features of the Ekster tracker, and try to compare it to the other devices along the way. Then, I will quickly address many of the low reviews you see on Amazon, most of which are ill-informed or, IMO, planted there to dissuade potential customers.The app is great. It works perfectly, it has a sleek user interface/design. It is very elegant and minimalist. all the buttons and options work instantly. This is a big deal to me, because the major problems with the Innway and the Orbit were that the app did not seem to respond in a timely manner. With those apps, I would have to tap the "find my device" button repeatedly before the tracker would respond. And changing the app's for the Innway / Orbit settings was also clunky and unresponsive. Location tracking didn't work on the Innway or Orbit trackers, either, but works great on my Ekster. My only gripe is that the Ekster is the only one of the three that doesn't display the current battery life of the tracker. This worries me because: what if it runs out of battery and is left in the dark somewhere? It will be hard to find, and if it can't "ring" when I try to locate it, that will be bad. I've only owned the card for about a week so far and I will be sure to update this review with the battery life if it ends up being a problem.In order to mitigate any battery problems, I keep the tracker in the "ID window" of my minimalist wallet. This is that pouch with the 'clear window' that is supposed to display your ID. Instead, I just have the tracker placed in there, facing outward so that it can absorb light when its sitting on the kitchen counter or on my desk at work. Hopefully this keeps it charged.This tracker is as thick as about 2 credit cards. This is likely due to the fact that the entire device has some sort of protective cover/sleeve wrapped around it, which gives it a smooth, soft vinyl feel to it. I imagine the components inside consist of a battery, a bluetooth transceiver, a small speaker and a small solar panel. The sound is not very loud, but it's loud enough to hear if you're in the same room. In other words, if you left it in your bathroom upstairs, you probably won't hear it from the living room downstairs. You will need to walk around in order to find it.Furthermore, THERE IS NO GPS INSIDE THIS DEVICE! If you're wondering "why no GPS", i'll tell you the rationale behind this. There is NO REASON to have GPS crammed into the card. This is because, in order to pull data off the device, you need it to be connected to a phone via its app. Your phone has GPS, so when the card is connected, the app uses the phone's GPS to update it's most recent location (i.e., the last time your phone 'saw' the device). This is more efficient for the card, because it saves valuable space and battery power. If the card itself had GPS, it wouldn't serve any additional purpose, it would just waste space and battery life and you wouldn't get any added benefit because the GPS data wouldn't go anywhere, it would need your phone to display the GPS data.IF YOU LOSE THE CARD AND IT IS DISCONNECTED FROM YOUR PHONE, IT CANNOT SEND YOU REAL TIME SIGNALS TO HELP YOU FIND IT! The only way this could work is if you purchased a cellular phone data plan and had the card continuously send you signals that tell you it's location. In this case, you would need to cram both a GPS receiver and a cellular transceiver into the card AND you would need to pay for a data plan so that the card will constantly send location data to a server somewhere. This is not only costly, but it will also eat up the battery life and significantly increase the size of the tracker. THIS IS AN UNREALISTIC EXPECTATION FOR A DEVICE THIS SMALL!Take your phone for example. Notice how big it is. Your phone does all these things, and you need to charge your phone at least once every day. Try it out for yourself: turn on your phones data, GPS, and bluetooth, then turn off the screen and don't interact with it until it dies. It will likely die after 24 hours. And just THE BATTERY in your phone is probably 3x the size of the Ekster tracker. Larger phones will last longer because they typically will have larger batteries, but even those max out at around 48-72 hours with ONLY the GPS, data, and Bluetooth running (i.e., screen turned off, no apps in use). Thus, it is unreasonable to shove real-time GPS tracking and data transfer into this small tracker.In order to address these concerns, device trackers will rely on BLE (Bluetooth Low Energy), which allows them to last for weeks or months. BLE requires some cell phone with the included app to be within about 100ft proximity in order to get some sort of location data from that device. Ekster advertises that the location can be crowd-sourced by other Ekster users. This means that if you tap the 'report my device lost' button, the Ekster app knows to look for it and sends notifications to other users who have the Ekster app (these notifications are invisible to the other user). So if another user with the Ekster app comes within close proximity to it, then their GPS will send coordinates to the Ekster server, which will notify you that it is somewhere near that other user. I've yet to test this feature, but I imagine that it's seamless to both you and to the other Ekster user that happened to come within close proximity to your lost tracker.And finally, to the guy who claims Bluetooth can be hacked: he's right, it can be. But that is a risk that you need to assess for yourself. The likelihood of someone hacking into your bluetooth on your phone is quite slim, and almost non-existent as long as you don't do anything. Bluetooth hacks can only occur when a phone user inadvertently allows a connection manually. In other words, you must have already allowed the connection in order for the hacker to 'hack into' your device. As long as you connect your bluetooth to only your Ekster tracker and don't connect to anything else, you will be fine.