Features 1、Made of aluminum alloy. Light weight, but it has a great strength and high performance. 2、The front derailleur is removed, the load on the bike is reduced, the chain cannot be dropped, and reduce the annoy of chain dropping. 3、The narrow wide design ensures that the chainring is more stable, effectiv ely protects frames from scratches, and can reduce friction and noise. 4、The ergonomic round design can reduce the load on the legs or knees, ensuring more comfortable and smoother riding. 5、The unique shape increases the contact area of the chain, improves the grip, and reduces the chain sag, making it easy to pass on uneven roads. Item Type: Bike Chainring Material: Aluminum Alloy Product Size: (Allowable Error of Manual Measurement) Outer Diameter: Approx. 168mm / 6.6in Adjacent Aperture: Approx. 74mm / 2.9in Diagonal Aperture Approx. 104mm / 4.1in Number of Teeth: 40T Package List 1 x Bike Chainring