From the brewery:

XX Bitter or Extra Extra Bitter is a blond, bitter ale containing 6% vol. Alc. It's famous for its very bitter and strong flavour. XX is made with pale pilsner malt and loads of Brewers Gold and Hallertau hop flowers. A perfect combination that has been nationally and internationally praised. This ale has been a real trendsetter for the current comeback of bitter ales in Belgium.

Only whole leaf hops are used.