Hi Parksy, I sent caktanks an email enquiry and they never even replied
The need for the vent cowl was to allow me to vent my batteries to the outside .
After searching high and low I never found a low profile vent cowl, I searched caravan, motorhome, marine, I’ve looked at clam shell vents, gas drop vents microwave vents, refrigerator vents and a few others and couldn’t find anything I liked the look of or were shallow enough to go on the side of the caravan wall, so I had to think outside the box and I think I've found a solution.