When you want to find the misplaced items, just need to do is to whistle or shout. Any loud noise causes the key finder to beep

Features100% Brand new and high quality Small in size, portable and convenient Whistle or shout within 7 metres to make it beep and flash, especially low whistle Beep with flash light for six seconds Powered by three AG3 button cell included 

Easy Key Finder Locator Find Lost by Whistle - Anti Loss