I'm totally sold on these PYREX tips, even though they have been going
through an evolution; O-rings, size specs.. etc.
Mine (510/901) will not fit on an Ikenvape 901 atty, but does fine on reg. 510's and DSE 901's. I have one tapered cobalt, and a clear non-tapered, with a clear tapered on the way, and a bulky 306 clear that works great.
The difference in dripping experience is so good that I just won't drip without 'em.