Window Bird Feeder - Extra Strong Suction Sups and Removable Seed Tray with Drainage Holes. windowsill Birdfeeders For Bird Watching Bird Feeders for Small Birds Squirrel Proof Garden Feeders

Safety Warning Make sure the suction cups areas on the glasses are clean before you put the cups on the glass. You can clean the glass with clean water/alcohol/cleaner. Also make sure the suction cups are also clean. Make sure both the suction cups and related glasses area are dry. When assemble the suction cups, make sure the press pressure are strong enough, no any air inside the cups. by tightening the nut, it would pull up the center of the suction cup, the tighter the nut, the stronger the suction.