Features 1、Made of steel, processing by heat treatment and precise grinding 2、HRC62, fine grinding, high size precision 3、Suitable for engraving machine ER chuck 4、Good elasticity and abrasion resistance 5、High precise clamping force, good grip stability Specification Description: Adopt high quality stainless steel material, good flexibility and wear resistance. High precision, tight and stable clamping. Features: Made of steel, processing by heat treatment and precise grinding. HRC62, fine grinding, high size precision. Suitable for engraving machine ER chuck. Good elasticity and abrasion resistance. High precise clamping force, good grip stability. Specifications: Material: Steel Diameter: 8mm / 0.31"(outer) 6.35mm / 0.25"(inner) Size: 2.5 x 0.7cm / 0.98 x 0.27" Weight: 5g(approx.) Package Includes: 1 x Engraving Adapter Package List