Over the collar fit - slip the collar through the holes of the bandana and fasten the collar as normal Around the neck fit - place bandana around neck and fasten the provided popper buttons. There are 3 buttons to accommodate looser and tighter fitting Over the collar size XS - 5 inches wide by a 4 inch drop (suitable for cats, chihuahuas, dachshunds, small breed puppies) S - 7 inches wide by a 6 inch drop (suitable for spaniels, cockapoos, small breed dogs) M - 10 inches wide by a 8 inch drop (suitable for border collies, labradors, bulldogs, medium sized dogs) L - 12 inches wide by a 9 inch drop (suitable for huskies, german shepherds, akitas, large breed dogs) Popper size XS - 9-12 inches wide with a 5 inch drop S - 13-16 inches wide with a 6 inch drop M - 17-20 inches wide with an 8 inch drop L - 21-24 inches wide with a 9 inch drop For best results handwash with warm water, dry flat, and do not iron directly onto any vinyl print i.e name personalisation etc.