Multipurpose: Ideal life helpers! Great to be used as holders for bird feeders, potted plants, toiletries or kitchen utensils and wreath hangers for decoration during holidays. Strong Suction: 1.8 inch large contact surface provides stronger suction which is able to hold up to 4 lbs. Tightly adhere to any smooth surface without falling off! Fit Smooth Surfaces Only: Work great on any even and non-porous surface like mirror, window, metal, ceramic tile, marble, etc. Punch-free design allows for installation within seconds. Clear & Invisible: Full transparency makes them easy to hide and won't disrupt the layout or styles of your decoration or arrangement. Ideally support your various hanging needs. Easy to Use: Just clean and dry both the suction cups and the glass surface before installation. Please soak them in warm water for about 2 minutes if they get warped. Pawfly 20 Pack 1.8 inch clear and thick suction cups are made of soft PVC plastic which is flexible for you to adhere them easily to any smooth surface such as glass, window, metal, marble or tile etc. Not suitable for wood, paint, grease stain, leakage and crevice walls. With tab to break the suction at ease when you want to release it.