18″ Concentric Curb Transition, Duct Size:18″, Designed to Drop Into The Curb and Convert The Square Duct Unit Connections to Round Duct, For Use with S1-1RC0501, S1-1RC0502, S1-1RC0503, S1-1R0504 Roof Curbs, Dims:10″H X 17-1/2″W X 21″D, Weight:9 Lbs, In Box, Made in USA.








