Schott Zwiesel (a brand of Zwiesel Kristallglas, AG) has a 130 year history of innovation and success, including such break through developments as the first machine made stemware and the first lead-free crystal glass. With the introduction of the proprietary Tritan® Crystal technique (the result of special additives such as titanium with a unique tempering process) Zwiesel has once again revolutionized the industry. Rigorous laboratory testing proves the brilliance, dishwasher safety, and break resistance of Tritan. Highly resistant to chipping and breaking even at its most sensitive areas - the rim and at the points where the stem joins the bowl and the foot. The glasses stand up to daily use and thousands of cycles in your dishwasher, without any blemishes or loss of brilliance.