-There are any combinations of Primary efficiency section, middle efficiency section, Sub-high efficiency section, super high efficiency section;

-Aluminum alloy frame，25mmPU foam sandwich panel;

-Good noise insulation, good heat preservation;

-Spring vibration isolators and soft joints available in the inner of the unit;

-5 gear manual damper;

-Filter compressed by spring compressor or four-corner screw;

-Pointer pressure differential gauge is standard, stainless probe;

-Impeller balance up to G2.5;

-The whole unit leakage lower than 3%@1000Pa(up to1%).