19" rack cases are the most common type of road case used for mounting a variety of audio devices such as signals processors, effects racks and power amplifiers. 19 inch is the industry standard width for rack mountable audio gear. ABS rackcases, commonly known as a flightcase, are regularly used by musicians as they are both light in weight while being extremely tough and durable. Sizes are measured in 'rack units' known as either RU or U, with a 2U / 2RU spec meaning 2 rack units of space. All 19" rack mount gear is sold in standard rack unit measurements, enabling neat and efficient racking.