Avoid the market on glass surface when vacuum.

After the suction cups vacuum the glass, sucker's shape will be leave traces on the glass. 

Becasue of the electrostatic friction. the washing machien unable remove them. You can find it with hot steam.

now, there are a type of suction cups protect cover to solve the matters. 

this cover was made with imported raw materials.  that's good at adsorption performance, air tightnee, no leak but durable. 

and easy to change new. 

put them on suction cups, then to move glass. perfect! easy and no market.