Flight computer. Whiz wheel. E6B. Regardless of what you call it, this manual calculation/conversion tool is a fundamental item for pilots of all experience levels. With this proven, manual device you can easily determine wind components/crosswinds, fuel burn, true airspeed, density altitude, time/speed/distance data, and much more. It's also great for easily converting between a variety of units - no batteries required! Includes an instruction manual and conforms to all examples used throughout Jeppesen's line of training materials. An extremely affordable, durable tool that's been a fundamental performance computer for generations of pilots.