I'm looking for a collar for a bird to stop him from pulling feathers.
I would get your collar from an avian veterinarian. The reason is that I don't believe any bird should have what is called an Elizabethan collar on its neck unless it has been recommended by an avian veterinarian. Most birds don't care for the collar and it could exacerbate what is already a situation that may have a psychological cause. Regarding feather picking, the first thing a bird owner should do is take the bird to an avian vet and have tests run to see if the feather picking is a symptom of a medical problem. If it is, the avian vet can treat the bird for the medical condition and the collar may not be necessary or only necessary for a period of time. — Ed.