These versatile CRL Wood's Powr-Grip® 4-1/2" (114 mm) Mounting Cups provide a reliable, temporary fastener on almost any smooth, non-porous surface such as metal or glass. Choose from either Cat. No. LJ45AMP with a 1/4"-20 x 3/8" (10 mm) stud or Cat. No. LJ45AMC with 1/4"-20 threaded insert. Both feature a red-line indicator to warn users of any vacuum loss, and check valves that allow re-pumping without the loss of the remaining vacuum. Both Cups come with a vacuum pad protector.