Many ignition failures have been attributed to inexpensive rotors that are built down to a cost at the sacrifice of quality. These heavy-duty ignition rotors fit better than others currently available, and all of the common causes of failure have been eliminated: there is no rivet to come loose, they are colored so there is no carbon (as used to make the black versions) to cause tracking, and the rotor-to-shaft fit is correct. Direct replacement for early type 25D distributors with either side-exit or top-exit cap. Ref: DRB101, DRB101HD, DRB101SP.