Key Alt is manufactured according to the Purity Law. The brewery uses its own yeast, which is a trade secret. The Altbier has an original wort content of 12.5%. The brewery obtains some of its raw materials directly from the region, partly because of the shorter transport routes. Since 2009, spring and winter barley has been grown in Ratingen exclusively for the key. In 2012 and 2014, the Schlüssel Original Alt won the gold prize at the European Beer Star in the Düsseldorf-Style Altbier category.