The Squirrel Buster® Plus is a premium Truly Squirrel-ProofTM bird feeder that Pays for Itself in Saved Seed®. When a squirrel gets onto the feeder, its weight will automatically close access to the seed. This model was voted BEST squirrel-proof bird feeder by Popular Science. The feeder is designed as a detachable component system: it comes apart easily for cleaning and no tools are required. An adjustable spring mechanism allows for selective bird feeding and a special Cardinal Ring makes it easier for Northern Cardinals to feed. Accessories like a Weather Guard, a Pole Adaptor for pole-mounting the feeder and a Seed Catcher Tray are also available. If ever a part is lost or broken, the Brome Lifetime Care policy will replace it free of charge, and the shipping is on us. We recommend filling this feeder with black oil sunflower or mixed seed.