Sprockets for Harleys that are machined from a tempered aluminium. This material is tougher than steel and of course much lighter to save on unsprung weight, so these sprockets are the choice of sport riders.

These rear sprockets are made for narrow 520 chains (5/8” x 1/4” pitch). Their object is to realize somewhat larger tires with as little drive train offset as possible. Sports oriented riders like the narrow chains for their lower rolling resistance.