I used these for an install of some DMX runs using Neutrik 5-pin XLRs. They finish off the job for a few extra pence and provide a dust and pin guard for unused inlets/outlets.
Use with the Neutrik MFD mount plate, also just a few pence and avoid the pain of getting an M3 nut and nut spinner onto the back of your D-type connector.
Decent plastic but I don't know how many open/close operations the hinge will last for. I'm sure the Neutrik quality will shine through...