Our 3M Roloc+ button plays an important role in the 3M Roloc+ attachment system and it's designed to drive 3M unitized wheels that contain a 3/8 in center hole. A threaded shank on the 3M Roloc+ button passes through the unitized wheel's 3/8 in center hole and twists into a Roloc+ holder. Then, the 3M Roloc+ holder (sold separately) can be mounted on the power tool, most commonly on tools featuring a 1/4 in collet chuck. The 3M Roloc+ button has an extended load bearing shank, which provides added bending strength for applications using unitized wheels where side loading occurs.