Word of caution, these studs cannot be driven out if this is a oem drum. The stud is swedged to drum. There was a special cutter made to chuck into a drill. It was hollow, so it could slip over the stud & cut the swedge away. I have seem guys destoy a drum trying to knock out the studs. There were two sizes, one for 7/16 studs & one for 1/2 studs. I used to have both of these, but i think all I have left is the 7/16 size.