Suitable for smooth - These do stick and hold wonderfully on a smooth (like a car or glass), however, any plastic suction cup not stick if there is any texture to the whatsoever. It's the nature of the beast. If air can get in, the suction not hold because it relies on creating a vacuum. Versatile Usage - perfect for tie down applications where there isn't an anchor point, cleat or other device to anchor conventional tie downs. Includes versatile wide gate spring hooks and attaches via heavy-duty webbing , These suction cups stick to smooth fiberglass surfaces like glass, boats, SUPs, cars and campers No Residues - No Glue -Strong Sticky gel base is added to the suction cup to provide stronger hold. The suction cup perform in cold or hot environment. Long Lasting hold, not come off remove it. Provide very strong grips on smooth ., Manufacturer: CTRLZS