Wood's Powr-Grip Vacuum Cups are specially designed, hand actuated cups that operate on a pump system, and create a vacuum under their gripping pad section. The pump plunger has a red band to indicate suction level at all times. When it shows less than 100% vacuum left, simply pump the plunger until you reach the original vacuum pressure without removing the cup from the glass! To release, just depress a trigger on the opposite end of the handle from the plunger. 

• 8" (203 mm) diameter
• Durable metal handle
• Vacuum-molded carrying case included to protect the cup when not in use
• Fast attachment on smooth, non-porous flat surfaces
• Red-line indicator warns user of any vacuum loss
• Check valve allows re-pumping without loss of remaining vacuum
• Release valve lever permits quick, complete release