- Allows for truing and tensioning of wheel using internal or external wrenches - Polyax design features a round shape of the head that works like a ball joint between the rim and nipple ensuring a better spoke/nipple line - Aluminum SL: 7075-T6 aluminum, special coating on thread and nipple surface to further reduce corrosion and reduce friction between spoke/nipple and nipple/rim. Secure Lock prevents nipples from loosening via a mechanical means instead of a thread locking compound or paste - Brass: nickel coated to ensure good corrosion resistance.