Hi, All I can say is WOW!! This is the best money I've spent in a long time. Hours of enjoyment. Key, in my opinion is to start off with a clean window. The suction cups on this particular model are over sized, which is a good thing. This feeder holds a good 6 to 8 cups of seed. It's nice because you fill the feeder from the top and it trickles down into each side when the need cups need filled. Nice and low maintenance. Thanks Wayfair