My b doesn't (usually) pull so I can't say for sure, but even at its tightest, the collar won't cut off air entirely. The tightness of the collar is limited; if you order one of the custom ones from Long Dog, you get to specify the smallest circumference of the collar. I would imagine a wide leather collar to be preferable to a thin nylon one for a puller, just because it won't chafe or cut into his neck as much.
