This package includes 4 suction cups with 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. They are perfect for tie down applications where there isn?t an anchor point, cleat or other device to anchor conventional tie downs. The suction cups are suitable for smooth surfaces only. They hold wonderfully on a smooth surface (like a car or glass), however, any plastic surface suction cup will not stick if there is any texture to the surface whatsoever. The suction cups are attached with sticky gel base - Much stronger hold strength ?? Double suction. No Residues - No Glue - Strong Sticky gel base is added to the suction cup to provide stronger hold. The suction cup will perform in cold or hot environment. Long Lasting hold, will not come off until you remove it. Provide very strong grips on smooth surface.