The Squirrel Buster Plus keeps out squirrels and some nuisance birds by using an adjustable weight mechanism that closes access to the seed. Features seed tube ventilation 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.