MasterKey has a unique, award winning, straight-line design that's intuitive and easy to understand. Unlike circular devices, there's no need to spin MasterKey to read the clear and simple graphics. Besides transposing between any two keys, MasterKey displays eight different scales, relative minor keys, and all seven modes. MasterKey is being used as a teaching tool for beginners and as an accurate reference tool for advanced musicians all over the world. Each MasterKey is made from heavy-duty ABS plastic for years of service. It also comes with a 15-page manual to help you get the most from this indispensable tool.