Keep your gaze bright. Compatible with the COAST HL7R headlamp, the Z100 set of four NiMH batteries recharge inside the headlamp by connection to a Micro USB cord. A battery charge indicator flashes red during charge-up and shines solid green when fully charged, and the overcharge/discharge protection circuits make powering up as simple and safe as possible. The set of four batteries is backed by COAST's one-year warranty against defects in materials and workmanship.