Models 0755(A) and 0756(D) Ceiling Radiation Dampers have been designed and tested for simple installation in specific UL design wood truss ceiling assemblies. They are UL Classified for use in specific 1 hour rated UL floor /ceiling and roof/ceiling designs. Model 0755 ships complete with thermal blanket and top inlet round duct connection. Model Series 0756 features a factory provided sheet metal plenum for steel grille/diffuser mount or ducted applications with duct collar(s). Models 0757-CB/-DB/-EB and 0763-FB/-GB come with a variety of plenum options or steel grille/diffuser mount applications. Models 0755/0755A are listed for UL designs L528/L546/L550/L558/L562/L574/L576/L579/L581/L583/L585/L592/M501/M503/M526 and roof/ceiling design numbers P531/P533/P538/P545/P547/P549/P552/P570/P580. Models 0756/0756D are listed for UL designs L528/L546/L550/L558/L562/L574/L576/L579/L581/L583/L585/M501/M503 and roof/ceiling design numbers P531/P533/P538/P545/P547/P552. Models 0757-CB/-DB/-EB and 0763-FB/-GB are listed for UL designs L528/L546/L550/L558/L574/L576/L579/L581/L583/L585/M503 and roof/ceiling design numbers P531/P533/P545/P547/P552.