So I have never bought or used sockets. I installed on my truck and wanted to use a grommet to prevent wire wear down the hole. I used a 5/16 bushing and the hole I drilled wasn't 5/16, I had to make a much larger hole. I'm not sure if that's how it usually works, but I found it a little frustrating. I wish they listed both sizes, the size of the hole needed and then the size of the hole for the bushing. Otherwise it gets the job done and seems to work fine for my application.