Made of high-quality carbide material, offering good flexibility and wear resistance. High precision with tight and stable clamping performance. Processed through heat treatment and precise grinding for durability. Suitable for use with engraving machines and compatible with various bit tools and chucks. Features good elasticity and abrasion resistance. Provides high-precision clamping force and excellent grip stability.Specification: Material: Carbide 6.35mm to 12.7mm: Inner diameter: 6.35mm / 0.25 inch Outer diameter: 12.7mm / 0.49 inch 6mm to 12.7mm: Inner diameter: 6mm / 0.23 inch Outer diameter: 12.7mm / 0.49 inch 8mm to 12.7mm: Inner diameter: 8mm / 0.31 inch Outer diameter: 12.7mm / 0.49 inch 10mm to 12.7mm: Inner diameter: 10mm / 0.39 inch Outer diameter: 12.7mm / 0.49 inch 10mm to 12mm: Inner diameter: 10mm / 0.39 inch Outer diameter: 12mm / 0.47 inch 8mm to 12mm: Inner diameter: 8mm / 0.31 inch Outer diameter: 12mm / 0.47 inch 6.35mm to 12mm: Inner diameter: 6.35mm / 0.25 inch Outer diameter: 12mm / 0.47 inch 6mm to 12mm: Inner diameter: 6mm / 0.23 inch Outer diameter: 12mm / 0.47 inch 6.35mm to 9.5mm: Inner diameter: 6.35mm / 0.25 inch Outer diameter: 9.5mm / 0.37 inch 6.35mm to 8mm: Inner diameter: 6.35mm / 0.25 inch Outer diameter: 8mm / 0.31 inch Package Includes: 1 Piece Router Bit Chuck Adaptor (4 Pack)