Visitation Control System complete with 350-250 15VDC 4A power supply; Insulated screw terminals for 32 units (16 pair); Audio balancing components; all mounted on 19’ by 10.5” mounting board for rack or wall mounting; mounting hardware included; completely pre-wired. Requires AC power. Telephone devices are sold separately. Wire/Cable between system and devices not provided. 22-26 gauge Telco wire recommended. This system provides direct one to one talk path for up to 16 pair of devices or 32 total devices.