Piece Hard felt Bob kit with 1/Mand, Bob Material Felt, Bob Shape Ball, Cone, Cylinder, Pear, Density Grade Hard, Head Dia. 1/4 in, Head Length 3/4 in, 1 in, 1 1/2 in, Number of Pieces 4, Operating Speed – Maximum 3,600 RPM, Shank Dia. 1/4 in, Shank Length 3/4 in