Use an oval-round connector to connect two pipes with different dimensions. It creates a transition from one pipe to another, usually to widen the diameter. For example, you can connect your fireplace with a masonry chimney flue.
Our dimensions for transitions always indicate the diameter of the bottom first. If the dimensions are Ø100/Ø130, it means that a pipe or flue outlet is widened from 100 to 130 in the direction of the smoke. Dimensions: Ø92/Ø120mm