The Cabernet glass is perfect for full-bodied, complex red wines that are high in tannin. The generous size of this glass allows the bouquet to develop fully, and smooths out the rough edges. It emphasizes the fruit, playing down the bitter qualities of the tannin, and allows wines to achieve balance. This product is made of clear crystal glass. Designed in 2004, RIEDEL The O Wine Tumbler was the first varietal-specific wine tumbler in history. O is an innovative take on the casual wine glass, based on the benchmark shapes of RIEDEL's Vinum series. Better yet, the O Tumbler fits into every dishwasher so broken stems are a thing of the past.