Best Ductwork Accessories Are Matched To Our Range Hood Requirements. These Elbows, Extensions, And Duct Transition Accessories Ensure Proper Air Flow And Volume Requirements. Refer To Individual Product Requirements For More Details. (Ul)(Li)For 8" Round Duct(/Li)(Li).025 Aluminum - Natural Finish(/Li)(Li)Attachment Collar 3-3/8" Long(/Li)(Li)Without Backdraft Damper(/Li)(Li)Intended For Make-Up Air Inlet Applications(/Li)(/Ul)