I just got in this quick release Herm Sprenger
I was having a terrible time with my other heavy duty Sprenger prong. It was almost impossible for me to manipulate. So far I've had no issue with the new one coming undone. I especially like it for quick trips to the yard for some obedience work. I may still use the other for classes. I can't get as close a fit with the new one ... or at least, taking a link out seems to make it too snug.