Chuck Size: 8mm, 6.35mm, 6mm (0.31", 0.25", 0.24") These are split collet converters for multiple purposes of chuck or collet sutability. Material: Made of carbide, high strength and hardness. Processed through heat treatment and precise grinding, durable to use. Usage: Used for trimming chuck conversion, engraving machines, wood router Features: Uses: Used for trimming machine, wood router, engraving machine chuck conversion Collet Chuck Adapter only, other accessories demo in the picture is not included. Specification: Material: Carbon Steel Quantity: 3 Pcs Package Content: 3pcs x Collet Chuck Adapter Size: As shown Product Specifications (Weight): 10g Delivery Quantity: 3 Pcs Application: Used to change the chuck of trimming machine and engraving machine. Note: The 1/4 (6.35mm) holes are mainly used in Europe and the United States, 6mm holes and 8mm holes are mainly used in Russia, Germany and other Middle Eastern countries.becomeveryrich