Chuck size: 8mm, 6.35mm, 6mm (0.31", 0.25", 0.24")These are split bushing converters for multiple purposes of chuck sutability or pliers.Material: made of carbide, high strength and hardness.Precise heat treatment and grinding, durable to use.Usage: Used for converting cutting chuck, engraving machines, wood router Features:< /b>Uses: used for cutting machine, wood router, engraving machine chuck conversionCollet Chuck Adapter only, other accessories demo in the picture is not included.Specification: Material: carbon steelSize:1. Large Head Diameter Outside: Approx. 11mm, 11mm, 11mm2. Small Head Outer Diameter: Approx. 8.8mm, 7mm, 7mm3. Hole Diameter: Approx. 8mm, 6mm, 6.35mm4. Total length: approx. 7mm, 8.4mm, 8.4mmQuantity: 3 PcsContents:3pcs x Collet Chuck AdapterNote: The data is manual measurement, please allow 1-52cm error, due to differences between light and screen, there will be a certain color difference, the specific received in nature prevail.