The packaged bundle includes one Tile Pro and one Tile Slim. The Tile Pro is the smaller, square-shaped Bluetooth tracker. It can be added to your keychain or kept with your electronics or even your luggage. The Tile Slim is the larger rectangle. It's about the size of a credit card and about twice the thickness. Stick that one in your wallet, notebook, or something like that. The Pro is water resistant, can be detected up to 400 feet away, and has a one-year battery that's user replaceable. The Slim's battery can't be replaced but it lasts for up to three years. It has a 200-foot range and is completely waterproof.