Stable Durable -----High precision, tight and stable clamping, improve work efficiency. Made of carbon steel, fine workmanship, high strength and hardness, provide good flexibility and wear resistance. Different Size-----2 each of 3 different sizes: 6mm/6.35mm/8mm meet your various needs,and 2 adapter nuts. Easy to carry-----Very Portable, Small, easy to store. Widely Used-----It's split bushing converters for multiple purposes of chuck or collet sutability.Suitable for engraving machine, wood router, trimming engraving machine etc. Specification Material: Carbon Steel Size: Hole Diameter: 6mm, 6.35mm, 8mm Big Head Diameter Outside: 11mm, 11mm, 11mm Small Head Outside Diameter: 7mm, 7mm, 8.8mm Over Length: 8.4mm, 8.4mm, 7mm Nut: Big Head Diameter Outside: 13mm Small Head Outside Diameter: 7mm, 8.5mm Over Length: 12mm Note: 1.please allow slight size error and color difference. 2.Please keep them away from children to avoid choking.