I bought three of these to go with the Nerf N-Strike Elite RapidStrike CS-18 Blaster I purchased, because in the internecine family Nerf wars that have been waged for almost years, dad is never supposed to be outgunned. They fit easily into the magazine well of the blaster, but don't bother trying to load 18 darts into it, because it will almost assuredly jam, forcing you to clear the chamber with your fingers, all the while being pegged by unrepentant children. I usually fill them to about 15 which seems to cut the jamming down, which allows me to pelt said children with over sixty darts in about thirty seconds. Oddly enough, the springs seem slightly different (and more reliable) in the clear magazine that came with the CS-18.