This is a 0.5 in. Hex output shaft with a 57 Sport mounting. We suggest using our red tacky grease, am-2768. We encourage that the user powers the gearbox continuously for 30 minutes without grease to allow the gear teeth to wear in. While we do design with short run times in mind, this 'run in' period for smooth gearbox operation, is recommended. Once this is completed, thoroughly grease the gear teeth periodically to ensure smooth operation.