we specialize in manufacturing dedusting equipment and many spare parts,here is the patent certification below: LHFSF bag filter Certification NO. HR-1999-183 FEF side inserted rotary switch flat bag filter Certification NO. HR-1999-184 LY-III pulse-jet bag filter Certification NO. HR-1999-185 ZC-III rotatory reverse blast flat bag filter Certification NO. HR-1999-186 LMN-III bag filter Certification NO. HR-1999-188 LY-Ⅱ low pressure pulse-jet bag filter Certification NO. HR-2001-068 LL2/6 catridge filter Certification NO. HR-2001-069 LMQ-7?96-A air case pulse-jet bag filter Certification NO. HR-2001-70 DMC impulse-jet bag filter