Mirror Finished Taper ground to AT3 or better specification ensures 80% or more contact with spindle to reduce harmonics and improve runout tolerance. Pilot Contact Inside bore are precision turned to engage a better contact with retention knob's pilot to increase rigidity. Taper End Face Precision turning surface finish provide perpendicular contact with the flange of retention knob to increase rigidity. Mirror Finish To achieve AT3 or better taper contact as an industry standard, our taper surface are precision ground on Shigiya CNC grinder from Japan. We are not satisfied with just meeting the industry standard, the surface roughness on the taper is maintained to mirror finish. High Torque Collet Nut The maximum torque is laser marked on the ER collet nut face to take the guess game out of the way to ensure proper amount of force should be applied while tightening. Innovative coating process significantly increases the clamping force by 75% compared to standard ER collet nut. More gripping force provides better rigidity and reduces the possibility of losing grip on the round shank which lead to expensive damage on cutting tools and work piece material. Asymmetrical O-Ring Internal clamping ring's shape is design to minimize out-of-balance compare to the standard off-center o-ring design from other standard ER collet nut, achieving 12,000 RPM without needed to drill holes on the collet nut body when placed on a dynamic balanced machine to preserve ER collet nut's body strength.