My friend and her daughter have them. The daughter had it clipped onto the d ring of the saddle and fell off her horse it made a bit of a noise inflating and it inflated amazingly quickly, she seemed fully protected around the neck and torso area. She actually forgot she had it on and got a fright at the amount of pressure and how much it inflated when she fell off. It certianly did the job and both were impressed by it. I think the new canisters are about £16.00??
Hope that helps. I've concidered getting one for when i back Vinnie next year, better to be safe than sorry