- Rennen Sprockets are precision machined from aircraft quality 7075-T6 Aluminum ( 83% stronger than 6061) and polished to a beautiful luster or available in Stealth Black, offering the highest performance at the right price. Rennen Sprockets are 3/16" thick and are made to take the abuse of the BMX Track, Trails or the Skatepark. Only Rennen Sprockets offer a single speed specific tooth profile which have been designed to extend tooth life. At 4.3oz (122 grams, 39T) this makes Rennen Sprockets one of the lightest on the market.