Black insulated 4mm test socket, ideal for panel mounting. This socket requires a cut-out of 7.8mm and is solder terminated. It can be used in the education sector and training schools for use with test equipment.
Seem to be pretty good! The nut is maybe a little lightweight but is standard thread so easy to change if required. Note that you can actually unscrew the plastic top from the main threaded metal socket quite a useful feature (for me at least)