Heavy-duty 41-inch diameter flap protected by rubber disk. Before you purchase any other feeder, ask experienced users how well competitors’ flaps hold up compared with Brower’s flaps. Molding process engineered to permit extra material to flow into center post for extra strength. Post has a 6-inch diameter base and is further supported by three partitions. High density polyethylene body. Hindered amine light stabilizer, the most effective ultraviolet inhibitor. Holds three different types of minerals. Can accommodate larger blocks up to 12 inches square. Also holds 200 lbs of loose supplement level-full.