From the brewery:

Westmalle Tripel (9.5%) is a clear Trappist beer, golden-yellow in colour, with amazingly fruity aromas of ripe banana and a lovely, subtle nose of hops. This full-mouthed beer offers finesse and elegance, with a mild taste and a creamy mouth feel, yielding bitter notes supported by fruit aromas. Enjoy the lingering, dry finish. The complex character of a Westmalle Tripel is derived from the slow brewing process and its re-fermentation in the bottle.

It was first brewed in 1934 and the recipe has not changed since 1956. It is made with pale candy sugar and has a very pale color produced from a mash of light pilsener malts. Styrian Goldings hops are used along with some German varieties and the classic Saaz pilsener hop. After a long secondary fermentation, the Tripel Westmalle is bottled with a dose of sugar and yeast. This beer holds up well in the bottle over time and seems to soften with age.