The Shieldmaster 45° Elbow can be utilized as a pair to easily offset the flue run or to be diverted through a wall, around a gutter or even to avoid beams.
You won’t require any additional sealants or silicone to seal all the joints. It has a unique push-fit locking system to make connection and disconnection very simple. The quoted diameter is the internal diameter and the surrounding insulation makes it 2” larger.