If a squirrel or larger bird tries to feed on any of the 4 spring-loaded perches, the X8's integrated design shuts every port simultaneously. And if a squirrel tries to hang from the top, the X8's weight-sensitive lid shuts every port, while the elongated tube further deters racketeering rodents. The cap is nestled within the tube to keep squirrels from accessing the seed. The large viewing window lets you know when it's time to refill, and the wide top opening makes cleaning and refilling a breeze! With a 2.5 lb seed capacity, the Squirrel-X8 keeps songbirds happy and coming back for more!