The crown piece is the part that goes behind the ears and ties the halter. It is measured from the jaw knots, for in indication of how long it needs to be measure from about halfway on the jaw behind the ears to the other side. Add about 20cm (8inches) to make the tie.
When your horse has a very long or wide you my need an extra long crownpiece.
If the crownpiece is too long you can cut of the acces and burn the ends to keep from fraying.
When tied you the end sticking out should not be able to reach the horse's eye for obvious safety reasons! You can als tuck the long end under the throat strap but we recommend cutting to to size if it's too long and only used on the one horse.