Smatree Smart & Cute Key Ring Cell Phone Protecting Tracker , Remote Control Wireless Bluetooth Device Cell Phone Lost Reminder with Timely Alert, Blue LED, Red LED Cell Phone Key Ring Finder/Protector 1pcs It works on cellphones with the function of Bluetooth. Remind .U reminds you do not forget your cell phone. Supports standard USB 5V charging. Build-in rechargeable Li-ion battery. While your first time use, please charge the battery power for at least 2 hours. We all have green, pink and coffee three colors, and we will send one of the three colors randomly.