Review on Industrial Grade Leviton 279 50 Amp Flush Mounting Receptacle: NEMA 14-50R, Grounding, Straight Blade, Side Wired, Steel Strap, Black by John Murphy

This device is exactly as it always was and still needs improvement. The guy who designed this either had no experience with industrial design or it looks like he never worked on anything. Yes it does what it says on the tin but with a little thought it will be a lot easier to install. It says it will work with #4 wire, but the holes are actually slightly larger than that, which is lucky because the plastic in front of the brass wire saddles isn't sloped or beveled toward the saddles, which would help a lot with your wire insertion. Instead, they're useless sharp square corners that make pushing a stranded cable through much harder than it should be.