Goes together with the inner flange and internal locking band (with centering extension). The outer locking band is on the surface For additional assistance, which makes it a much better method. A passive fire protection solution for air distribution systems, smoke Management and kitchen area grease ducts All through this https://tituswodrg.smblogsites.com/37051238/how-much-you-need-to-expect-you-ll-pay-for-a-good-grease-tight-extract-ductwork