I bought this on the strength of the seller stating it fitted all modern condensing boilers, a more accurate description would have added “except for Vaillants” This is 7” at the rear, 5” at the front and the depth is 4”. So it won’t fit yours if your vent sticks out more than 4”. But I should have measured my flue. So it’s new and just as it came in the post today
eBay