The world-classic beers of the Rodenbach brewery, and several similar products from competitors, mainly in West Flanders, are a distinct style without a name. They are more sharply acidic, leaner, more reddish, half-brothers to the brown ales of East Flanders, with the additional difference that they are often filtered and pasteurised. Their sharpness makes them perhaps the most quenching beers in the world, and their acidity renders them very food-friendly. The sharp acidity, and some of the colour, derives from ageing in large, fixed, wooden tuns.