Pin kits provide master- wafers, top- pins, and springs for a thorough cylinder rebuild. Replace any worn parts, rekey, lubricate, and reassemble. Check to see that the keys work well, check remaining customer keys if any and reinstall.
Pin kits offer a comprehensive approach to cylinder rebuilds by providing master wafers, top pins, and springs.  The process involves replacing worn parts, re-keying the cylinder, lubricating it, and then reassembling it. The goal is to ensure that all keys function properly and any remaining customer keys are reinstalled.