Best advice I can give is, "go to the no crow caller website, find the question and answer board, there are detailed instructions on how to apply the collars. Follow their suggestions thoroughly!
Also spend a couple hours watching videos on YouTube about the no crow collars, they will help you...
We have three Cockrells with "no crow collars on them", we are extremely happy with all three. One is a Easter egger the other two are French black copper Marans. They just turned six months old, we check them every two weeks to make sure they're not getting too tight since they're still...
I ordered mine this past weekend, because of the United States Post Office not being open Monday they didn't get shipped till Tuesday, earlier today I receive notification they're supposed to be delivered tomorrow. Anxious to get them on and adjusted, sure like the Cockrell and hate to steal him...