Weha Double Suction Cup
The Replacement Double Suction Cup for Suction Cup Assembly are designed specifically for the Weha Suction cup assembly.
They have the hook and lever on the underside of the handle to clamp onto the special grooves in the rail of the Suction cup assembly so that they don't come off.
Diamond Tool Store offers a number of Suction Cups and larger Glass Vacuum Lifters.