The Squirrel Buster Suet is TRULY SQUIRREL PROOF! The weight of an adult squirrel automatically closes the seed ports, denying access to the seed but not harming the squirrels in any way. Also effective on large birds. All materials exposed to squirrels are made of chew proof metals or RoxResin. A remarkable 100% chew proof, waterproof and UV stabilized material. The squirrel proof suet feeder is designed to be dismantled by hand making cleaning and filling easy. The Squirrel Buster Suet Feeder has an amazing Crumb Port so that no suet is wasted! Crumbs fall to the Crumb Port where birds recycle them. The feeder holds Two 5"x 5" suet cakes.