Unmounted Extra long-lasting Silicone Bonded abrasives have silicon carbide, silicon dioxide and aluminum oxide abrasive compound in a silicone binder. They are suitable for grinding, smoothing, and cleaning glass, high speed steel, and other tough materials. Includes Foredom 3/32″”shank: A-M9 threaded mandrel and A-M1 screw mandrel. 4 abrasive grits in 3 shapes with 1/16″”Arbor Holes – listed below. Abrasive Color/Grit: Black /Coarse, Brown /Medium Coarse, Green /Fine, Blue/ Extra Fine 6 – Wheels of each grit 22 x 3 mm (.866″”x .118″) 6 – Tapered discs of each grit 22 x 3.5 mm (.866″”x .138″) 6 – Cylinders of each grit 7 x 20 mm (.275″”x .787″)