The Unico System Fiberglass Ductwork, exclusively manufactured by Unico, Inc., is the perfect choice when deciding on a plenum while installing the Unico System. A natural sound attenuator that absorbs noise, Unico’s square fiberglass ductwork comes in 3 sizes, ranging from 6.5” to 9.5”. With a full line of fittings and accessories available, our Square Fiberglass Ductwork makes installing the Unico system even easier.