The Twin Wall to Twin Wall Increasing Adapter allows a secure connection between any twin walled pipes of different diameters for Shieldmaster twin wall only.
Shieldmaster twin wall flue is CE approved for use in the UK, designation number EN:1856-1 T450 N1 D Vm L50050 G60. Please note, this item comes supplied with a locking band only in the lesser diameter and will increase the internal diameter of your flue system by one inch.