The Squirrel Yankee Flipper is the definitive squirrel proof birdfeeder. Birds love to eat from it and squirrels love to try, but they can not! The way this feeder keeps squirrels out will provide hours of entertainment. The weight activated perch is calibrated to a squirrels weight. When a squirrel steps on the perch a connection is made with a motor that makes the perch spin, and the squirrel is flipped off the feeder. The unit comes with rechargeable NiCad batteries and a battery charger. Feeder is 30 inches long and has a 5 pound holding capacity.