The O series, by Riedel, is a stemless crystal wine glass collection that is perfect for everyday use and casual events. Like the Vinum Series, the glass shape is designed to showcase the character of specific types of wines. The flat-bottom tumbler shape won't accidentally tip and break, which makes it handy for casual entertaining or outdoor events where breezes could present a problem. The stemless design fits effortlessly into your dishwasher.