Wood's Powr-Grip  4-1/2-inch vacuum cup with black polycarbonate mount, 1/4 - 20 thread insert

Durable polycarbonate accessory mount with threaded insert for attaching equipment.
Provides a reliable, temporary vacuum mount, without drilling holes.
Rubber vacuum pad will not mark or damage most surfaces.
Attaches to flat or curved, smooth, nonporous surfaces.
Red-line indicator warns user of any vacuum loss.
Check valve allows repumping without loss of remaining vacuum.
Lift tabs on vacuum pad edges permit instant release.
Supplied with vacuum pad protector.

Vacuum Pad: Concave, 4-1/2" [11 cm] diameter (model LJ45)
Minimum Radius for Curved Mounting Surface: 12” [305 mm]
Height to Mounting Platform: 2-1/64" [51 mm] on flat surfaces;
2-13/64" [56 mm] on surfaces with maximum curvature.
Load Capacity: 40 lbs [18 kg] per vacuum cup