One way mirror film lets you see birds--and they can't see you. Seed flows from the two hoppers to the center of the feeder where you get an unobstructed view. Add different seeds or blends in each hopper, you’ll attract more species of birds. A crystal clear roof protects seed from weather, and two heavy-duty suction cups firmly adhere to any window. Easy to clean and fill too. Holds 2 pounds of seed. 11-1/2 x 8-1/2 x 3-1/2 inches.