Features: Craft from high strength aluminum alloy and stainless steels, this kits is light weight, reducing overall bike weight and improving cycling efficiency. Transform your multiple speed bike into a safe single speed machine with the single speed conversion kits, designs for enhances climbing power. Perfect for mountain biking adventure, and city commuting, casual ride, and bicycles modification, ensuring great performances in various ridings conditions. With its user friendly designs, the conversion kits allows quick installation without professional tool, making it a great selection for those seek reliability in their cycling. Great for mountain biking enthusiasts, street cyclists, and also bike repair technicians look to upgraded or maintain their bicycles easily. Specifications: Materials: Aluminum Alloy+Stainless Steels Color: As The Picture Shows Styles Optional: Eight Styles is Available as Shown in the Picture. Inner Diameter: approx.3.45cm/1.35in (More Size Detail, Please See Picture.) Package Includes: 1 Set of Single Speed Flywheels note: Please allow 1-2cm error due to manual measurement. Please make surer you not mind before your bid. Due to the differences between different monitors, the picture may not reflect the actual color to the item. Thanks!