I use a couple of these under their 'baby-cage' (My broody hen uses this cage to brood the chicks and then lives in there until she deems it to be a good time to find new 'digs'. When she does, I place these PVC fittings under the two front corners of the cage to allow entry/exit for the chicks, yet bars adult birds from entry. I put the two holed side on the exterior of the cage to give the chicks a choice of direction and it offers stability to the cage. Pictured is 6" fittings, perfectly big enough for young chicks yet too small for adults.
