Atoplee MT3 to MT4 Morse Taper Drill Sleeve Reducing Adapter for Lathe Milling Material: 45# steel Accuracy: 0.015mm, Hardness: 50 HRC Inside Taper No. * outside Taper No. *Outer diameter *inner diameter*full length:MT3 * MT4 *31.6mm *23.5mm *132mm Package Included:1pc MT3 to MT4 Morse Taper Adapter