Excellent choice for 12 Volt DC outlet. Mounts solidly with a securing nut behind the panel and a cover plate to make a neat installation. The diameter is reported as 1 1/8 inches, I used a 28mm hole saw and the was able to "screw-in" the body of the socket for a nice tight fit in thin plywood. It has spade lugs for connections so it's easy to connect/disconnect with crimp on terminals. The cover seems to seal well, so I would call it water resistant. I would buy this again and again.Excellent choice for 12 Volt DC outlet. Mounts solidly with a securing nut behind the panel and a cover plate to make a neat installation. The diameter is reported as 1 1/8 inches, I used a 28mm hole saw and the was able to "screw-in" the body of the socket for a nice tight fit in thin plywood. It has spade lugs for connections so it's easy to connect/disconnect with crimp on terminals. The cover seems to seal well, so I would call it water resistant. I would buy this again and again.