YIYI

YIYI is a standard bluetooth low energy product, Link Lost Service, Immediately Alert Service are included.
You can use this App connect to YIYI and attach it to keys, bikes, bags or any valuables you wish to protect. While either one is moving out of the range, iPhone will ring and show a alert view, and record the location in the 'Disconnect records' only if you open 'Location Service'.

If you hand YIYI but forget where the iPhone is or hand iPhone but can't find your YIYI, don't worry, they can find each other. Push the button on YIYI to make the iPhone ring. Or use this App to make the YIYI buzz and blink.