1、For the usage of MT shank, taper shank drills, reamers reducing 2、The reducing drill sleeve is made from high quality 45# steel, sturdy and durable in use 3、Adopts overall quenching process, long life, lasting, strong shock-resistance 4、High accuracy, inside and outside are very smooth 5、Easy to store and maintain, very practical tool Features: For the usage of MT shank, taper shank drills, reamers reducing. The reducing drill sleeve is made from high quality 45# steel, sturdy and durable in use. Adopts overall quenching process, long life, lasting, strong shock-resistance. High accuracy, inside and outside are very smooth. Easy to store and maintain, very practical tool. Specifications: Model: 1-2 2-3 3-4 Material: 45# steel Hardness: HRC58 Size: MT1- MT2: length: 92mm / 3.62in, bottom hole diameter: 12mm / 0.47in MT2- MT3: length: 112mm / 4.41in, bottom hole diameter: 17mm /0.67in MT3- MT4: length: 133mm / 5.24in, bottom hole diameter: 23mm /0.91in Weight: 569g Package included: 1 x  MT1- MT2Taper Adapter 1 x  MT2- MT3 Taper Adapter 1 x  MT3- MT4 Taper Adapter Note:  Please allow 1-3mm error due to manual measurement. Thanks for your understanding.