Ankway Durable Acrylic Window Bird Feeder for Outside with 3 Strong Sticky Suction Cups, Removable Tray, Drain Holes for Bluebird Cardinal BirdUltra Sticky Suction Cups: Secure three strong suction cups sticks tightly on the window or most surfaces which ensures the feeder remains secure to your window even in extreme weather for SEVERAL YEARS and without leaving any nasty mark on your window or other surfaces. Clear and Durable: Sturdy design made from premium crystal clear acrylic which ensures the bird feeder is sturdy and highly transparent. Enjoy a close up view of wild birds and you