I bought one of these and when it arrived was too small to get over my female DS's head.
I've since bought a different collar type as I wanted something to stop her pulling during heel training and on walks: Canny Collar.
You may want to consider this as an alternative to the prong collar. [I've not used the prong so I can't comment on it, but it looks like it too would be effective for vigorous pullers].
The Canny is one of [3] similar type collars giving you added control, the others were the Gentle Leader & Halti collars. I liked the Canny's design a little better because it applies pressure to the dog's snout from behind versus from underneath & to the side. I felt it would be less inclined to jerk her head about.
You can find it on Amazon or TheDogOutdoors [which has a video]:
http://www.thedogoutdoors.com/canny-col ... 5QodvlEhfg
I don't work for either of the above nor do I have any vested interest in the product, just trying to suggest alternatives and I'm not trying to hijack this thread.
My DS took a little time to get introduced to this collar as it was pretty foreign to her having a strap over her nose. She actually did a few forward summersaults trying to remove it. But lots of high value treats and just getting her out and heeling/walking with it did the trick in fairly short order.
She's quite the heeling angel with this collar on. I found I can be a lot easier/more gentle with leach corrections. I also found it good to keep the slack on the lead to a minimum or the nose loop may slide off.
Tim