Material: Bike Narrow Wide Chainring is Made of 7075 aluminum alloy, CNC cutting, with positive and negative designed to prevent the chain from dropping, strong force. Specifications: Crank BCD ( hole distance) is 130 mm. Easy To Use:Mud discharge oblique mouth to prevent sediment accumulation.The thickness of each tooth is processed by CNC, which can work seamlessly with the inner and outer links of the chain to suit your riding, and reduces friction and noise. Round Bike Chainring:The anode is colored to prevent oxidation, so that an oxide film can be formed on the aluminum surface, which effectively protects the aluminum alloy body. Anti rust, durable. Note:Bike Chainring is Suitable for most 130 BCD cranks, please make sure your crank BCD and number of tooth specification carefully before purchasing. Specification: Material: aluminum alloy Size Chart: 50T:20.9cmx20.9cm or 8.23inchx8.23inch 52T:21.6cmx21.6cm or 8.50inchx8.50inch 54T:22.5cmx22.5cm or 8.86inchx8.86inch 56T:23.3cmx23.3cm or 9.17inchx9.17inch 58T:24.1cmx24.1cm or 9.49inchx9.49inch 60T:24.9cmx24.9cm or 9.80inchx9.80inch Package Includes: 1xBike Chainring Note: Please allow slightly errors due to manual measurement and different monitors.