Mercury Multi Door Controllers are Advance Technology Door Access Control Security Panels for All types for Doors Elevators Barriers and Secure Lockers. HID Mercury Access Control System Range includes models like HID Mercury LP1501 for 2 Doors HID Mercury LP1502 for 2 Door 4 Reader Connectivity expendable up to 64 Doors. Mercury Door Controllers HID Mercury LP2500 Master Intelligent Controller comes without onboard IO Circuits and require models like HID Mercury MR16IN-S3 Serial 16 Input Output Interface Panel HID Mercury MR50-S3 Serial Input Output Single Card Interface HID Mercury MR52-S3 Serial Dual Input Output Card Reader Interface and HID Mercury MR62E is Reader Interface Module with POE for 2 Doors 4 Readers 6 Inputs 4 Outputs.