CRL Vinyl Suction Cups contain U.V. stabilizers that protect the cup from yellowing in the sun. The metal clamp will hold small signs, radar detectors, thermometers, bird feeders, notes or advertisements in its spring-loaded jaws. This small diameter cup will hold up to 1 lb. (.45 kg). Cups generally adhere to smooth, non-porous surfaces with little effort. There are 25 cups in a package. Important Notes: Do not exceed the weight limit of this cup.