I've got one but have not used it. The catch all strap broke when I pulled on it. I reported this to BB, and they are looking into something stronger.
Remember, this strap was a prototype, and not the final issue, so I expect some changes will be forthcoming.
They have not fixed the problem as yet to my knowledge.
They have received several comments and suggestions from selected prototype users, and are evaluating how these suggestions can best be added to the final version of the collar.
I would think they will post something on the BB web site when the final version is for sale.
I got a couple of them very cheap at a recent hunt test. I put one of them on my TTPro500 receiver and have only used a couple times. Haven't seen a problem yet. However, I gave one of them to a retriever pro trainer friend of mine and like the very next day he showed me a broken strap. The little thin, lightweight piece of plastic tubing that connects the buckle to the other part broke and the rubber tubing pulled off. He almost lost his receiver in the water because of it. He said that IF he had lost his receiver (new TT Pro500), then he would have contacted BB to see if they were willing to replace it? I plan to replace my TT strap right away! E-Collars cost to much to risk that! They are going to have to do better than that before it will work. Maybe use stronger plastics like high impact Kydex, etc. and use a thin piece of braided stainless or piano wire, etc. instead of the plastic tubing. It is a very nice concept however but when the e-collar strap is snug I don't think the dog's neck swells that much during heated training to really justify such a device. Seems sort of a 'novelty' idea?