Features 1Bicycle single disc gears are made of strong aluminum alloy, the material is wear resistant, resistant to deformation, and high in strength. The appropriate thickness can ensure that they will not bend. 2The ergonomic round shape effectively utilizes punching to generate more yarn traction, reduces the load and fatigue of the legs or knees, and ensures a steady ride. 3The unique tooth shape design increases the contact area of the chain, improves the grip, and reduces the chain sag, allowing you to easily pass through bumpy roads. 4The narrow and wide tooth design of the positive and negative toothed chain ensures that the chain is fixed, effectively protects the frame from scratches, prolongs the wear life, and reduces friction and noise. 5The advantage of the positive and negative chainrings, the removal of the front derailleur, greatly reduces the load on the vehicle, the chain can not be dropped while riding, and the trouble of chain dropping is reduced. Item Type: Bicycle Positive and Negative Sprocket Material: Aluminum Alloy Size: Outer Diameter: Approx. 160mm/6.3in Adjacent Aperture: Approx. 74mm/2.9in Diagonal Aperture: Approx. 104mm/4.1in Number of Teeth: 38T Applicable: 38T Single Disc, More Inclined to Mountain Horse Players, Cruising 32+ or with Expansion Discs, Competition Players. Package List 1 x Positive and Negative Gear Disc