Schott Zwiesel Tritan Crystal will not become dull even after many washes. The Schott Zwiesel crystal glasses can be use often without the daunting task of hand-washing and polishing lots of glasses after entertaining. A set of 6 Cognac Glasses.Each glass can hold 0.62Ltr and measures 11.2 x 17.1cm. We recommend that you use your dishwasher for these fine glasses. This will bring excellent results time and time again.