I ordered three from nocrowroostercollars.com, and they only sent me two. No backorders listed (the invoice said "all shipped". They did not respond to my e-mails and to this day have not sent me another. So, negative experience there.
However, the collars work amazingly well. The two roosters that got the collars freaked out and tried to "back out" of the collars for about 15 minutes, but after that they were fine. I had to re-adjust them several times, but once I got them adjusted correctly the rooster's crow is reduced to 5-10% volume. You can barely hear it across the yard, and I am positive the neighbors will not be able to hear them. I am VERY pleased with their performance.
For my third rooster I cut 2 strips of velco, stuck them back to back with their sticky glue sides, then wrapped them around like I did the no crow collars. It worked just as well, although there seemed to be less room for error (it was easier to over-tighten and chock the roo).
Now, if they would only respond and let me know what is going on with the rest of my order.
I hope my experience helps someone.