Inquiry (采购产品): Exaust fan louvers I have difficulty maintaining louvers on 9 - 30" general exaust fans. After only 1 year the spot welds and rivots that hold the flaps in place fail. Shortly thereafter eack flap falls off and I lose heat from the building, get rain infiltration and bird infiltration, etc. Do you have strong shutters/louvers that I can purchase. **** Hidden Message ***** John Brock 19112 Company: U.S. Navy E-mail: john.brock@navy.mil **** Hidden Message ***** john.brock@navy.mil