They have straps which fit round/under wings. There's an art to fitting them.... But I swear by them for orpingtons, the cockerels are very heavy and the favourite girls can end up losing feathers very easily.
Thanks Mrs B, your always so nice about my birds . Still nice and mild where you are I see, not got up to scorchio quite yet.
The saddles are made from canvas Rick, as Mrs B says they stay on with straps under the wings, I do like some of the offbeat images you conjure up in your head though.