most folks who use a prong collar also use a "Safety" link - a little connector line between the prong and a regular collar (buckle usually) so that when (Not if) the prong opens you still have a leash on your dog. i had a Herm collar come loose three times in a couple years of use on a daily basis and was glad I had the safety collar hooked up (Last two times anyway!!!!).

just a thought!