... opening, which provide security.3.Low gravity to set up water tanks, and save more energy when using.4.Rotating wire ... . Demountable batholith which can use in step or corner.Accessories: Water tank,Floor brush, Pad drive, Aluminum alloy sanding discs (4KG), Blocks ... hard floor ,wax,spray grinding maintenance,and carpet nursing together Multi-functional Brushing Machine FC-1517