The master station for the AI-C-123LA features a push to talk, release to listen button. Communication at the C-D is hands free. The C-ML/A also has a N/O dry contact for door strike connection and mounts to
AI-C-123L-A: Single master set Set includes a door station (AI-C-D) and a master stations (AI-C-ML/A). Additional masters may be added. Each master requires a separate power supply, either the SKK-620 or 4 "