The bulkhead version is used for panel mounting through a wall of e.g. an instrumentation box.To prevent angular displacement,Website:http://www.honorconnector.com, the through-hole is D shaped. The advantages of a bulkhead mount are that it is technique and that the connector is replaceable. XAHonor bulkhead mount SMA connectors includes SMA female bulkhead connectors and SMA male bulkhead connectors, which can designed to terminate to PCB mount as well as cables mount. SMA Bulkhead Mount ConnectorsPicturePart NumberDescriptionGenderMaximum FrequencyPolarityOrientationData SheetSMA-JYDSMA Straight  Crimp Plug Bulkhead  50 OhmPlug(male)18GHzStandardStraightSMA-KY2CSMA Straight Bulkhead Jack  RG178  50 OhmJack(female)12.4GHzStandardStraightSMA-KYHDC5SMA Straight Bulkhead Jack 50 OhmJack(female)18GHzStandardStraight