The weight loading for this Adams 85mm suction cup is 5.5kgs (12lbs) on a suitable surface.
This suction cup is used with a screw and fixes securely to any clean, dry, slick, shiny, glossy, smooth, non textured, non-porous surface like glass, mirrors, glossy plastic, glazed ceramic tiles, car body work etc. Check out the technical drawing image above for measurements.