Features1Hardening Technology: The flywheel adopts hardening technology, with greater wear resistance, durability, high temperature resistance, corrosion resistance, rust prevention, no deformation, high durability and good impact resistance. 2Strong Compatibility: The high accuracy of the bicycle freewheel tooth shape, toothless design and strong compatibility make riding more possible. 3Hollowed: Reduce the riding load, achieve a good balance between strength and weight, and is easy to install and use. It is an ideal choice to reduce the weight of bicycles. 4Easy to Install: This flywheel is easy to install, professional manufacturing, direct replacement of old or damaged flywheel, accessories for mountain bikes and road bikes. 510 Speed: Bicycle flywheel is made of high strength steel, 10 speed, number of teeth are 11 13 15 17 19 21 24 28 32 36T.SpecificationItem Type: BicycleFreewheelMaterial: High strength steelGross Weight: 720g/25.4ozSpeed: 10Number of 10 Speed Teeth: 11-13-15-17-19-21-24-28-32-36TPackage List1 xBicycleFreewheel