A strong sticky gel base is added to the suction cup to provide a stronger grip. The suction cup works in cold or hot environment. These stick and hold beautifully on a smooth surface (like a car or glass), however plastic suction cups will not stick if there is texture on the surface. Each anchor can hold up to 20 pounds, lasts a long time and won't come loose until you take it out. Offers very strong grips on smooth surfaces. Includes versatile wide door spring hooks and attachments via heavy duty webbing. These suction cups stick to smooth fiberglass surfaces such as glass, boats, cars and RVs. Perfect for traveling, you can connect two cars to hang your clothes, tent, awning and you can hang anything, convenient to use and carry. It works on most smooth surfaces not porous. Cup hooks last as long as needed.