Yup, it is wireless and that white piece goes into the tank. It can be hung up or placed on dry substrate (how I have it in my rosy boa tank). As with anything you don't want to drench it with water (it does not have a gasket making it water proof) but I have accidentally spritz them a few times without issue. It can rotate showing outside temp and humidity and inside the tank temp and humidity in case you want to know the room temp and humidity outside the tank.