ER40 collet clamp: 1.Made of special elastic stell material 2.power clamping ability,precise accuracy ER40 collet set : ER40-(7PCS/SET) ------6,8,10,12,16,20,25mmER40-(15PCS/SET)-----4,5,6,8,10,12,13,15,16,18,20,21,22,25,26mmER40-(23PCS/SET)-----4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26