The Hollyland Solidcom SE-4S is a 2.4 GHz full-duplex wireless headset intercom kit for four people, used by camera crews, event and church production teams, stage managers, referees and coaches who need hands-free, simultaneous team talk without a base station. The kit includes one master headset and three remote headsets (single-ear), four Li-ion 770 mAh battery packs, a 6-slot charging base and a USB-A to USB-C cable; all headsets are pre-paired at the factory so the system works out of the box. Each headset uses dual-microphone environmental noise cancellation (over 20 dB reduction), push-to-talk and a latching talk/mute boom, with automatic frequency hopping to avoid interference. Hollyland rates line-of-sight range at up to 350 m (1,100 ft). Battery life is about 10 hours on the master (with four remotes connected) and 12 hours on a remote, with detachable batteries and USB-C charging in under three hours. Frequency response is 150 Hz to 7 kHz, and each headset weighs about 185 g with battery. The headsets are water resistant but not waterproof.