Duncraft"s newest window feeder comes with a mirrored back. Birds can only see their own reflection as they eat, so sudden movements within the house won"t startle them. You get continuous close-up views of the birds! Lift the chimney on top and turn it upside down - it doubles as a funnel so you can fill the feeder with less spillage. Fill with any bird seed or seed mix. The seed is contained in the sides of the feeder where birds feed from four feeding ports. Two wide perches let several birds land at once, so you get to see even more bird activity! Plastic construction, attaches to the window with four suction cups. Approximately 2.00 inches deep x 13.00 inches wide x 18.50 inches long.