The Hollyland Solidcom C1 Rechargeable Lithium-Ion Battery is designed to provide power for both the master and remote headsets used in the Solidcom C1 intercom system. The amount of battery time in the master headset depends on the number of remote headsets in use; with 5 remote headsets connected, the battery will last for approximately 5 hours; with 3 remote headsets in use, the battery life is 6 hours. Each remote headset will last for up to 10 hours on a single battery charge. Use the 4-slot or 8-slot charging case and its power adapter (case and adapter available separately) to charge the battery. The battery fully recharges in 2.5 hours