Pinless peepers are used to counter cannbalism in flocks. They call them "pinless" peepers because there is a type of peepers that are metal and have a pin that goes through one nare to the other and are secured so they can't fall off. It doesn't hurt the chicken since there is no septum in chickens.
Pinless peepers are plastic and are flexible with prongs instead of pins. They are installed using snap ring pliers which work opposite of regular pliers and hold the peeper prongs apart to slip into the nares.
There is an adjustment period to learn to see with the peepers blocking forward vision. Most chickens adjust within minutes to the peepers, but some have more trouble. It can help to ease this transition with treats on the ground which can help the chicken to focus downward to find the food. The treats soothe the stress of this adjustment.
Thanks for this! Will keep it in mind