Warren & Brown YellowDuct reducers allow different size ducts to be joined together. They are available with or without covers.
WBT P/N: TC1279-238AReducer, 100mm x 50mm to 50mm x 50mm (with cover)
WBT P/N: TC1279-240AReducer, 100mm x 100mm to 50mm x 50mm (with cover)
WBT P/N: TC1279-91AReducer, 100mm to 50mm (with cover)
WBT P/N: TC1279-97AReducer, 50mm x 50mm to 30mm x 30mm (with cover)