... down drafts channel, proliferation wind channel and so on . The silk ties cooling to use the two-sided symmetrical blowing; the wind ... type drafts2,drafting efficiency higher,low consumption3,drafting silk balance,the single silk discrepancy is smaller 4,long distance of drafting ... , fill drafting 5,It effective to divide silk,Hatching uniformity6,system sealing off ,easy to control IF YOU ...