Steel shelving system This mobile shelving provides optimum storage space for maps ,charts,CD,etc to prevent damage. A precision ball bearing system allows you to easily slide drawers in and out, even when they are filled to capacity, and safety stops keep the drawers from over extending. 1.Handle: steel-made crank handle, the structure is ratchet automatically linked,it can stop at the vertical position after the closure . 2.Transmission system: Two-way overrunning clutch structure, using one-third force, three speed change and the middle driving method. Chain:motorcycle-specific chain; Wheel :gray cast iron; Axis and short axis:φ20mm45 # cold-rolled solid round steel; Chassis: 204 double-row to the radial ball bearingsin high quality ; There's a reliable degree in the center of a straight line, so that the body frame can be balance and brisk when it sliding. Also you can move single-column or multi-column at the same time. 3.Braking devices: Each unit have the braking device, ensure personal safety; Each combination of groups have a total lock device; Theres a higher level of anti-theft capability and confidentiality. 4.Sealing devices: The contact surface of each column have a buffer and seal. A dust-proof plate on the base and an anti-rat plate onthebottom . There's no gap when you close up it. It has good function such as dust, fire, anti-rat and so on. 5.Spraying equipment: Use the most advanced automatedelectrostatic spray line