CRL Wood's Powr-Grip® 10" Vacuum Cup With Mounting Plate has a silver aluminum accessory mount with 1/4"-20 and 3/8"-16 thread tapped holes for attaching equipment. The cup attaches to flat and curved surfaces with a minimum radius of 13" (330 mm). The aluminum accessory mount has both 1/4"-20 and 3/8"-16 thread tapped holes for attaching equipment. Red-Line indicator warns user of any vacuum loss. The check valve allows re-pumping without loss of remaining vacuum. Easily replaceable handle/release valve and plunger. Supplied with vacuum pad protector.