The Hollyland Solidcom C1 Pro Rechargeable Lithium-Ion Battery is designed to provide power for both the master and remote headsets used in the Solidcom C1 and C1 Pro intercom systems. The amount of battery time in the C1 Pro master headset depends on the number of remote headsets in use; with 5 remote headsets connected and the ENC function on, the battery will last for approximately 5 hours; with 7 remote headsets in use and the ENC function on, the battery life is 4 hours. Each remote headset will last for up to 10 hours on a single battery charge.