MCIL and MCBH are the widely used micro-circular wet-mate underwater connector pairs (SubConn compatible). **MCBH is bulkhead-mounted**, threaded through the wall of pressure housings, with short internal pigtails inside the enclosure. **MCIL is inline cable connector**, overmolded onto free cable ends. They mate together directly with matching pin count and opposite gender. Both share the same pressure, electrical and wet-mate performance, suitable for deep-sea ROV, AUV, subsea sensors and ocean instruments. The core difference lies in mounting form: choose MCBH for housing penetration ports; use MCIL for cable extension, quick disconnect between cables and field serviceable wet connections.