The Unico System® UPC-61 Round Supply Air Plenum Adapter, Galvanized, Steel
The Unico System® Round Supply Air Plenum Adapter, Series: UPC-61, 8 in Dia, For Use With: Model MB3642x Blower Module, Steel, Galvanized
All Unico System supply plenum adapters feature a rectangular to round transition. The UPC-61-X (See table below for Part number match-up.) allows air to transition gradually from the blower outlet to the main plenum.