The Standard Abrasives Unitized Mandrel secures a 2-3??Standard Abrasives Unitized Wheel to a rotary tool for edge deburring and finishing applications. The silver button fits wheels with thicknesses of 1/8??or 1/4??and the black button accommodates wheels with thicknesses of 3/8??and 1/2?? Use this mandrel with a Standard Abrasives 913 or 933 Unitized Wheel (sold separately).