[Easy to install]:These buffing wheel are 1/2" center hole fits most bench grinder.[Professional design]: The buffing wheel is 70plys, much thicker to last long service term and provide larger surface area. Thick concentric sewn circles design holds plys together more stiffly so greater pressure can be applied.[Usage]: The power rotery tool buffing wheels ideal to polishing wood,metal, cast iron,brass, aluminum bronze and stone etc[Make your work easy]:The extra thick buffing polishing wheels are 70 ply, Extra plys can improve work efficiency.DIAMETER: 6 inch,1/2" Arbor Hole, H: 1" (70 ply) Material: Cotton. ***Attention: Due to its fine cotton buffing wheel, it would have a little flying fibre during first time working.