We have Tile, I have one on my keychain and have actually found my keys using it! (they were in the back of the car where I had set them down to get groceries, not in the house when I was looking for them later) One other time we realized the keys were NOT left at a store (we thought they were) instead they were in my laptop case, in a pocket I never use. I also have one in my backpack and suitcase. The batteries are not user replaceable, we just got our new replacement tiles. I really like it.