Ultralight™ Rear Chainwheel (437U-520-38GBSI) by Renthal®. Tooth Quantity: 38. Finish: Silver. Chain Pitch: 520. Renthal™ Ultralight Rear Chainwheels Renthal Build Championships. Renthal Ultralight™ rear chainwheels are manufactured to extremely tight tolerences from a special material developed to withstand the rigours of supercross, motocross and enduro racing. The 7075 T6 aluminium alloy rear chainwheels are 66% lighter than steel, yet incredibly durable. Their advanced tooth profile, concentricity and accuracy of fit provide maximum power transfer and long-life. Renthal's combination of a very high strength base material and an exceptionally hardwearing surface result in significantly increased chainwheel life over other brands. Self-cleaning mud grooves help prevent dirt build-up. This top-grade product is expertly made in compliance with stringent industry standards to offer a fusion of a well-balanced design and high level of craftsmanship. Manufactured from industry-leading materials using up-to-date equipment, it ensures everlasting reliability and enduring value. This product is distinguished by total quality assurance, unsurpassed by anybody else.