Just thought some may want to know how we do our large windows so they may be kept open all night in summer and still keep the flock safe from all predators (except maybe a bear-bears go where bears want to go, of course). This method was just tested over the last two nights by a large raccoon who tried in vain to gain access through this window--his foot prints were on the window ledge, showing he was standing on his hind legs, trying to push into the coop. Naturally, the screen held tight. Heard the 9 week old cockerel who roosts on that short bar closest to the window alarming loudly on the baby monitor. If that had been chicken wire, he'd be dead since the coon would have reached through the wire and pulled him through, eating him one bite at a time, or just ripped into the coop and killed everyone inside. This is the window in the newest coop which houses our Belgian D'Anvers. The sashes can be lowered from the top or raised from the bottom from outside. The interior screen is made from a 2x2 frame backed by hardware cloth which is attached by screws backed by washers. The screen is installed on the inside of the coop, hinged on the left side. Closure is by two spring loaded gate hooks, one top and one bottom, on the right, then for added security, a bolt is screwed into the wall, through a hole in the 2x2 frame and held there by a wing nut on the outside of the frame. The only time we need to release the wing nut is when we want to clean the interior of the window. See pics below.