Bulk Sapim nipples in a variety of styles - see type column for part specifications Standard Polyax - The round shape of the head of the polyax nipples work like a ball-joint between the rim and the nipple ensuring a better spoke/nipple line Secure Lock - Locking mechanism that prevents nipples from untightening during wheel truing, machine compatible Double Square - Allows the use of internal or external spoke wrenches - wrench flats above and below the rim interface rather than standard slotted spoke nipples Secure Lock 2.0x2mm Individual Brass Silver