The Squirrel Buster Plus keeps out squirrels and some nuisance birds by using an adjustable weight mechanism that closes access to the seed. Features a patented seed tube ventilation system to keep seed fresher, adjustable perches and attachable cardinal ring. Disassembles for cleaning, is chew and rust-proof, with a 3 quart seed capacity and Lifetime Care. It was voted BEST squirrel-proof bird feeder by Popular Science.