Product instruction:2-0.7 (0.2mm-0.7mm)_x000D_ Diameter of motor shaft is 2 mm. Fit max 0.7mm drill bit. Also fit 0.2 mm to 0.7 mm drill bit._x000D_ Concentricity adjustment method: Before lock bit need to adjust the concentricity,otherwise there will be a violent vibration,power on rotate awhile on the smooth surface of the floor or glass, lock bit after bit concentric._x000D_ _x000D_ Specifications:_x000D_ Material: Brass_x000D_ Size: 25mm(L) x 8mm(Dia.)_x000D_ Diameter of backshaft (match the motor shaft): 2mm/2.3mm/3.17mm_x000D_ Shaft-Max Drill Bit Size(min-max): 2-0.7 (0.2mm-0.7mm), 2-1.2 (0.7mm-1.2mm), 2-1.5 (1.0mm-1.5mm), 2-2.5 (1.8mm-2.5mm), 2-3.17 (2.5mm-3.2mm), 2.3-0.7 (0.2mm-0.7mm), 2.3-1.2 (0.7mm-1.2mm), 2.3-1.5 (1.0mm-1.5mm), 2.3-2.3 (1.6mm-2.3mm), 2.3-3.17 (2.5mm-3.2mm), 3.17-0.7 (0.2mm-0.7mm), 3.17-1.2 (0.7mm-1.2mm), 3.17-1.5 (1.0mm-1.5mm), 3.17-2.0 (1.4mm-2.0mm), 3.17-2.5 (2.0mm-2.5mm), 3.17-3.17 (2.5mm-3.2mm) 1This recessed table design on the front of the chuck cone prevents the direct entry of dust and iron chips during work, which affects the accuracy of the tool holder. 2The slot of the collet hole adopts a grinding process, which is suitable for high?speed processing. 3After cryogenic treatment, the wear resistance of the collet is significantly improved. 4The accuracy and life of the repeated chuck can be increased by about 50%, and the performance is stable. 5Used in milling, boring, drilling, tapping operations or various CNC, engraving machines and other equipment.1pcs drill bits chuck (come with 1 screw)