Type 43 

Type 43 or SMZ coaxial connector series was originally designed for British Telecom use in their digital networks within the telephone exchange for circuits from 2Mbit to 640Mbit.  These 75 ohm connectors were adopted by other network operators around the world.  Type 43 evolved into HDC43 and UHDC43, all with the same standard interface meeting BS9210 F0022 and BT’s RC8003 standards, but each having different body sizes to suit alternative equipment practices.  Type 43 connectors feature a secure push-pull latching mechanism and gold plated inner and outer contacts for extended life.

For details; http://www.coax-connectors.com/products/connectors/type-43.aspx