can anyone tell me what size hex bit is required for brava sump plug ?

seems like 12mm is a common fiat size
https://www.fiatforum.com/search.php?searchid=860641

its bigger than anything i had lying around, i asked at my local motor factors and they had the right size, cant remember what it was but they knew without looking, i think they said its a standard transmission key? it does fit the gearbox filler plug on a few cars.

I brought a 12mm hex as that was listed as Fiat. It didnt fit but a 9mm does!