I am not an electrician by trade, so I can only give you a layman's impression of these boxes. Please excuse the lack of appropriate terminology. The construction of the box is plastic, very strong plastic, it doesn't look like cheap plastic at all. There are 4 cable entry slots in the box, 2 on top and 2 on bottom. I used these socket boxes that I installed on a workbench. The metal bench had cutouts in the legs for sockets. These boxes fit sockets perfectly and the box attaches to the back of the leg, covering the socket and all connections. Very cheap price with the add-on program.