Type 54 

Type 54 connectors are a variant of the 75 ohm DIN 1.0/2.3 series of RF connectors.  These micro miniature connectors are designed to meet the British Telecom RC9333 specificaton and use the same tooling and assembly methods as the Type 43 series.  Used in Telecom applications the Type 54 connectors feature a push-pull coupling and are fully intermateable with the DIN 1.0/2.3 series.

For details; http://www.coax-connectors.com/products/connectors/type-54.aspx