A SO239 mount with "new style DV" plug fitting underneath.
The mount is for use with leads fitted with the "new style" DV elbow plug which has a male pin on it (see additional picture). The mount is also supplied with a small "pin" (see bottom of picture) which allows you to use it with a lead that has the "old style" DV plug on it.
Made by Sirio and designed to match their range of SO239 fitting antenna (eg Hypower 3000/4000), but equally suitable for any make of antenna which has a SO239 fitting.
Good rubber seal underneath and supplied complete with a screw-on weather cap.