Chuck head size: 8mm, 6.35mm, 6mm (0.31inch, 0.25inch, 0.24inch). Premium Quality: Made of steel, has good flexibility and wear resistance. High Precision: Suitable for engraving machine, wood router. perfect woodworking tool. Application: Suitable for automobile manufacturing, mold making, machinery manufacturing, etc. Scope of application: carving machine, trimming, milling machine, wood milling engraving head installation and transformation, and increasing the fixed carving head usage scope. Adopted steel material, good flexibility and wear resistance. Portable, high-precision, tight and stable clamping improves the efficiency of the work. Content: 3pcs x Collet Chuck Size: as shown Product Specification (Weight): 5g Quantity delivered: 3 rooms Note: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement.