Sapim has three types; oval small, large and round.
I guess that the oval small are for cx-ray, oval large are for cx and the round are for laser/race type of spokes, am I right? Can anyone correct me if I`m wrong?
AFAIK, the nipple washers are suppose to reinforce the rim, carbon ones or alu without eyelets, at the nipple ... so the hole of the washer is always round and not a function of the spokes you are planning to use
... but there is different shapes to adapt to the rim, and it's shape