1. 9 PCS SET: Comes with 9pcs router collet adapter in different sizes, this set will surely satisfy your different working needs. 2. FIRM CLAMPING: This router chuck not only ensures firm clamping, but also achieves high precision and stable holding. 3. PRACTICAL USE: Used for CNC machine tool chuck conversion, suitable for drilling tools and chucks with different characteristics. 4. CARBON STEEL: Forged with premium carbon steel material, which also has high flexibility and wear resistance. 5. GOOD DURABILITY: Processed by heat treatment and precision grinding, not easy to deform, durable for long term use. Specifications: Item Type: Router Collet Adapter Product Material: Carbon Steel Product Color: Inner Dia x Outer Dia x Height: Approx. 6.35 x 12.7 x 28mm / 0.3 x 0.5 x 1.1in 8 x 12 x 28mm / 0.3 x 0.5 x 1.1in 6 x 12.7 x 28mm / 0.2 x 0.5 x 1.1 inch 6 x 12 x 28 mm / 0.2 x 0.5 x 1.1 inch 6.35 x 9.5 x 30 mm / 0.3 x 0.4 x 1.2 inch 10 x 12 x 27.5 mm / 0.4 x 0.5 x 1.1 inch 8 x 10 x 25 mm / 0.3 x 0.4 x 1 inch 6 x 8 x 25 mm / 0.2 x 0.3 x 1 inch 6.35 x 8 x 25 mm / 0.3 x 0.3 x 1 inch Function: can be used for clamping drilling tools, boring tools, drilling machine engraving, reamer, etc. Package List: 9 x Router Collet Adapter Note: Please tighten the cutter head when using it and only work after it is firm and stable.