Description Made of aluminum alloy material, light weight, high strength and durable. Unique appearance, personality, corrosion-resistant. Easy installation, quick release screw nut suitable for bike rear This serves to distribute the pressure of the nut over the part being secured, reducing the chance of damage to the part and making less likely to loosen as a result of an uneven fastening surface. Mountain bike road bike fixed gear DIY modified accessories. Specification: MaterialAluminum Alloy Screw Height: Approx. 9mm/ 0.35inch Screw Outer Diameter: Approx. 15mm / 0.59inch Nut Outer Diameter:Approx. 22mm/0.87inch Nut Inner Diameter:Approx.10.5mm/0.41inch Nut :Approx.3.5mm/0.14inch Package Includes: 2 Pieces Rear Nuts Note: Please allow slightly difference due to manual measurement. Color may be slightly different since different monitor. Thanks!