These inline duct blowers feature belt driven DWDI forward curved blowers for high efficiency and low sound levels. The RDB cabinet housing is constructed of mill finish galvanized steel. The RDB-2 twin duct blower, consists of two inline duct blowers joined together with angle iron support. For balanced air supply, twin units utilize a common shaft. Capacities range from 350 CFM to 8,700 CFM and up to 2.0 in. wg.