Material: Made of 7075 aluminum alloy, CNC machined, with narrow-wide tooth design to help prevent chain drop and provide strong performance. Specifications: Crank BCD (bolt hole circle diameter) is 130 mm. Easy to Use: Features mud discharge slots to reduce sediment buildup. Each tooth is precision CNC machined to work smoothly with both inner and outer chain links, ensuring efficient operation, reduced friction, and lower noise. Round Bike Chainring: Anodized finish helps prevent oxidation by forming a protective oxide layer on the aluminum surface, providing rust resistance and long-lasting durability. Note: This bike chainring is compatible with most 130 BCD cranks. Please verify your crank's BCD and required tooth count before purchasing. Specification: Material: Aluminum alloy Size Chart: 50T: 20.9 cm x 20.9 cm / 8.23 inch x 8.23 inch 52T: 21.6 cm x 21.6 cm / 8.50 inch x 8.50 inch 54T: 22.5 cm x 22.5 cm / 8.86 inch x 8.86 inch 56T: 23.3 cm x 23.3 cm / 9.17 inch x 9.17 inch 58T: 24.1 cm x 24.1 cm / 9.49 inch x 9.49 inch 60T: 24.9 cm x 24.9 cm / 9.80 inch x 9.80 inch Package Includes: 1 x Bike Chainring Note: Slight variations may occur due to manual measurement and differences in display monitors.