Perforated access flooring is without foamed cement inside. The top and bottom metal panels and upper cover of the product are all punched with ventilation holes. And the ventilation rate of the product is between 18%-32%. The damper is used for adjust the air flow. Perforated access flooring is widely used for the place where ventilation is required under the floor such as satellite earth stations room, office building, computer room, program-controlled telephone switchboard room. Type: Aluminum series and Steel series(bare series) Size: 600 x 600 x 35mm( steel series), 600x 600 x 40/50mm(Aluminum series )