Roll-Out Laying Nests, in which the eggs roll out to the front or the rear (depending on the model), are made of sheet metal with heavy-duty plastic nest bottoms, perches, and collection baskets, resulting in minimal egg breakage and 'floor eggs.' Compared to wooden-constructed units, which can harbor lice and bacteria, these nests are rust/rot/corrosion-free and more easily sanitized, and their high front and back panels limit scratching litter out of the nests. To lower transit costs, they are shipped 'knocked down' (with assembly instructions provided).