McGard UHS security nut set (4 nuts + 1 wrench). To increase security, the UHS series nuts and bolt head are equipped with a rotating ring. which makes it extremely difficult to open them without a special wrench. The UHS series meets the Thacham 4-level security category. A compressed air wrench must not be used to tighten the security nuts! Each package comes with an ID number. You can order a spare chuck using this code!