This squirrel proof feeder features a weight sensitive metal ring of perches which drop under a squirrel's weight which closes the seed port to the see. It contains a patented waterproof ventilation cap that allows moisture to escape...so the seed stays dry. This feeder has adjustable perch lengths and a cardinal ring attachment that allows you to only feed birds you desire. It has a lifetime guarantee. It holds 5.5 lbs. of seed. Disasssembles easily by hand and is very easy clean.