This is the keychain device that locates a misplaced iPhone from up to 25' away. The unit connects via Bluetooth to an iPhone running a free app and causes the phone to sound an alarm or vibrate at the touch of a button on the keychain device, revealing its whereabouts. The unit can also be set to alert you when you've unknowingly left the iPhone behind by maintaining a constant wireless connection with the phone and sounding the alarm when the devices are more than 25' apart. The app can also help you to locate the keychain device if it is ever misplaced. Included CR2032 battery lasts up to 8 months. Compatible with iPhone 5, 4S, iPad 3, or 5th generation iPod. 2" L x 1 1/4" W x 1/3" D. (1 1/2 oz.)