[High-quality materials] The chuck of the engraving and cutting machine is made of carbon steel materials, which has good flexibility and wear resistance. [ Hole diameter] 6mm/6.35mm/8mm, 3 sizes meet different usage needs. Also comes with 2 nuts. [Woodworking Tools] The router collet is suitable for engraving wood milling, automobiles, molds and mechanical engineering. Is the perfect woodworking tool for engraving machine, wood router. [Easy to carry] The router bit chuck is easy to carry, has very precise clamping, tight and stable , and improve work efficiency. [Easy to use] Fine workmanship, stable performance, very easy to use. Features: Diameter of the hole: 6/6.35/8mm. Quantity: 6pcs (2pcs for each size) +2pcs nuts Material: carbon steel. Height: 3 20mm pieces, 2 pieces 8.4mm, 1 piece 7mm High strength and hardness. Easy to use. Durable in use. Package includes: 2pcs * 6mm Collet adapter. 2pcs * 6.35mm Collet adapter. 2pcs*8mm Collet adapter. 2pcs*nuts 2-3cm difference exists due to different measurement way , please confirm the detailed size before ordering, thanks for your understanding. on & cooperation. Due to the different monitors and light, please allow a slight color difference.