Comparison of Rubber Sucker & Sponge Sucker
I.Different use
Round rubber sucker is made of rubber. It's suitable for smooth surface boards, such as glass sheet, marble board, steel plate etc.
Square sponge sucker is made of high strength sponge. Its vacuum pump is enlarged, specially designed for handling different kinds of heavy and rough surface plates, for example marbles, floor slab, ceramic tile, steel board, wooden board etc.
Sponge suckers are not recommended to lift glass(because of the rugged surface of glass).
However, sponge suction cups are widely used.