Description: These adapters are made of high quality steel, hardened and tempered, precision ground inside and out for high concentricity. The tapered shank allows the tool to be inserted directly into the machine spindle to facilitate high torque applications such as large cutting diameters. Features: Made of high quality 45# steel, durable, wear resistant and long service life. Adopt overall quenching process, strong impact resistance. High precision, fine workmanship, inside and outside are very smooth. Easy to store and maintain, very useful. There are 4 types to choose from. For the use of taper shank cutters, taper shank drill bits, taper shank reamers, improving work efficiency. Specifications: Material: 45# steel Type: MT1 to MT2, MT2 to MT3, MT3 to MT4, MT4 to MT5 (optional) Hardness: 50 HRC Type D(mm) d(mm) L(mm) External Taper(MT. NO.S) Internal Taper(MT.NO.T) Inner Hole Length(mm) Weight(g) MT1 to MT2 17.78 12.065 92 2 1 56 89 MT2 to MT3 23.825 17.78 112 3 2 67 174 MT3 to MT4 31.267 23.825 140 4 3 84 350 MT4 to MT5 44.399 31.267 171 5 4 107 1000 Package Included: 1 x Taper Drill Guide