Mine don't actually have straps. One the picture of the silkie family (momma, baby, daddy) the pic of the momma shows a long piece of elastic. It never bothered her but it was a lot longer than it needed to be.
I make my own chicken diapers and after looking at pictures and reading about all the others, I am satisfied that the ones I make are superior in comfort and practicality. I have not started making them commercially but do intend to do so.
I kept about 5 chickens in diapers all winter in the...