When the item doesn't know where it is, open the cell phone app to check it, and you can according to the map. When the phone or other items can not be found Double click on the anti-loss device, the phone will sound an alert tone. By clicking the alarm in the APP, the item will automatically sound Double click the round button of the anti-loss device, and the phone will automatically sound. When the phone is more than a certain distance from the item, the item will automatically sound an alarm to remind to get back the lost item. and compact, easy to pick up without effort. Bluetooth version: Bluetooth 5.0 Use system: IOS/Android Effective distance: 15 meters Standby time: 6 months Battery model: CR2032 Type: Locator size:38 x 38 x 7mm Colour:B: Black Material:ABS Package Contents: 2 x Locator 1 x English manual Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.