The Perky-Pet Squirrel Slammer Wild Bird Feeder features a distinctive weight activated slammer that closes its ports instantly under a squirrel's weight. The slammer also has an adjustable weight setting so you can decide which birds to keep out. The high quality metal base and ports prevent squirrel damage and the plastic clear cover acts as another squirrel deterrent while keeping your seed dry. The Squirrel Slammer Feeder can hold up to 3.5 lbs. of seed.