COB LED Built-in acceleration sensor for Kinetic mode (Automatically turns on High mode when deceleration is detected.) Mounts securely to the seat post with the rubber band (12-32 mm) Lithium-ion polymer rechargeable battery USB rechargeable (Micro USB cable included) Low battery indicator 3 modes * Charging time: 2h Mode memory function Battery Auto Save (The mode automatically changes to flashing when the battery power gets low.)