You are buying Sapim Brass BAT REDUCTION NIPPLES 13g in Silver. Two options exist: those for gauging a 2.3mm/13g Spoke so as the nipple fits into a standard sized rim (i.e. you might want extra thick spokes but whilst still using a normal rim), or those for gauging a 2.0mm/14g spoke up so as the nipple fits into a larger holed rim (such as those found on e-bikes). Please choose the right type ;-).
“The round shape of the head of the polyax nipples works like a ball-joint between the rim and the nipple ensuring a better spoke/nipple line..”
I use these nipples day in, day out, as a professional wheelbuilder. You can also find all of Sapim’s other nipples through my webstore here.