For CNC machine tool chuck conversion, High precision,suitable applicable to different specifications of the bit tool and chuck Engraving Bit CNC Router Tool Adapter after heat treatment and precision grinding,fine grinding,concerted and high precision size. heat treatment,has good flexibility and abrasion resistance. Clamping force,high accuracy,good gripping stability. Commonly used in the engraving machine spindle motor folder knife,with the engraving machine collets use. Suitable for engraving machine ER collet. colour:black Material:High speed steel Size:6.35 to 3.175mm Package Contents: 6* tool conversion sleeve Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.