This is a very neat product in a simple design with smart technology. We decided to use this in our hot tub to keep an eye on the temperature. The product arrived in a package with clear concise product features described on the back and a QR code on the side to allow you to download the app for Iphone or Android very easily to start using the device after setup. I recommend using the QR code, because when I tried searching the Android play store there were several options available, so you could easily pick the wrong one. The water Thermometer comes with 2 AA batteries to help you set it up, very nice. I always love it when a company thinks ahead and includes the batteries for you. A++. To install the batteries simply unscrew the cap,remove the internal unit and slide the clear plastic battery cover to the right (follow the arrow imprinted on the battery cover) and install the batteries. Reinstall the battery cover. Now, look closely on the underside of the mechanism. You will find 2 buttons, one will be directly under the "A" and one under the "B" marked on the top side of the unit, you will probably need to feel around for them, as it is hard to see them with the naked eye. Once you have found them, push the "B" button once, this activates the system to start syncing with your phone. You will see the top light up red, which lets you know the system is activated and ready to go. When putting the device back into the bottom piece be sure you place it in correctly as it has to sit just right or the top will not screw on correctly. Once you have this done, you are now ready to install the string which comes with it to allow it float around but not float into the skimmer. You are now ready to place the device in the water and begin to get readings. The device will record readings over a period of time as well, if you would like. This product is genius!!! I have been offered this item at a highly discounted rate for an unbiased review of the product. If you found this review helpful, please click yes. Thanks! https://www.amazon.com/Ivation-Bluetooth-Water-Thermometer-Bathtub/dp/B01HORL74E/ref=cm_rdp_product