Please take time to check the matrix below carefully. You should select based on the main duct Ø. This is shown “Ø1″ on the diagram and matrix. This inlet or main diameter is then reduced to the diameter shown “Ø2″, this will always be smaller.
The length of the reducer is calculated as follows :
L = (Ø1 – Ø2) + 50 + (2 x 58) mm