Chuck Size: 8mm, 6.35mm, 6mm (0.31", 0.25", 0.24") These are split collet converters for multiple chuck or collet sutability purposes. Material: Made of carbide, high strength and hardness. Heat treatment and precise grinding, durable to use. Usage: Used for converting trimmer chucks, engraving machines, wood router Features: Uses: Used for trimmer machine, wood router, converting of Engraving Machine Chuck Collet Chuck Adapter only, other accessories demo in the picture is not included. Specification: Material: Carbon Steel Size: 1. Large Head Outside Diameter: Approx. 11mm, 11mm, 11mm 2. Small Head Outside Diameter: Approx. 8.8mm, 7mm, 7mm 3. Hole Diameter: Approx. 8mm, 6mm, 6.35mm 4. Total Length: Approx. 7mm, 8.4mm, 8.4mm Quantity: 3 Pcs Contents: 3pcs x Collet Chuck Adapter Delivery quantity: 3 pieces Product color: black Product size: 120 * 234mm Note: Manual measurement, please allow an error of 1 - 3cm!!!