High quality materials - These nuts are made of vinyl flexible rubber material, which is wear-resistant and corrosion-resistant. The thread protector has excellent flexibility and insulation performance, as well as a sturdy structure that can effectively absorb impacts. Product size - Rubber end cover combination kit includes 9 sizes (2 x 16mm, 3 x 17mm, 4.5 x 17mm, 6 x 17mm, 7 x 17mm, 8 x18mm, 9.5 x 17mm, 12 x 25mm, 20 x 27mm) Easy to use - choose the appropriate nut inner diameter and length. It is recommended to choose a nut slightly smaller than the outer diameter of the product to be protected. You can trim the thread protector safety cover to the desired length. Widely used - circular end caps are perfect for use with metal chair heads, furniture, tables, bicycles, boats, fence railings, and can also cover screws and bolts. It can be applied to any circular tube and provides additional protection to prevent damage to the tip and tip rod. The packaging includes - you will receive 400 rubber bolt covers (200 black, 200 red). Having sufficient thread protectors will enable you to protect more bolts or reuse them for other purposes. Colour:Red & Black Material:rubber Package Contents: 400 x Screw Caps(2mm black and red 20 each, 3mm black and red 20 each, 4.5mm black and red 30 each, 6mm black and red 20 each, 7mm black and red 30 each, 8mm black and red 30 each, 9.5mm black and red 20 each, 17mm black and red 20 each, 20mm black and red 10 each)