The Kensington Proximo key fob slips onto your key ring and connects to the iPhone 4s or 5 (or an iPad 4) using the Bluetooth 4.0 low-power wireless signal. There are two main benefits: If you lose your keys, you can run the app and do a quick location search within about 30 feet. The key ring can also alert you audibly if it senses your phone has been lost. The kit includes the key fob and one extra tag, which you can use for another item. Extra tags cost $25 each. [$60;]