The E6B flight computer is a circular slide rule used in aviation and one of the few analog calculating devices still in widespread use in the 21st century. These flight computers are used during flight planning to aid in calculating fuel burn, wind correction, time en route, and other essential flight calculations. In flight, the device can be used to determine ground speed, estimated fuel consumption, and updated estimated time of arrival. The reverse side is designed for wind vector calculations, such as determining the effect of wind on speed and course. It is commonly known by the nickname "whiz wheel". Manual E6Bs remain popular with some pilots and in certain environments due to their lightweight, compact size, durability, ease of one-handed operation, speed of use, and lack of dependence on electrical power. Although digital versions may be easier for beginners, many flight schools require students to learn with mechanical E6Bs, and pilots are encouraged to bring mechanical models to FAA written exams and checkrides for required calculations. Product Category: Flight Computer Product Number: E6B Application: Pilot training, practice, flight planning Color: As shown Material: Plastic Size: 9.05 x 4.72 x 0.19 inches Package Contents: 1 x E6B Aviation Flight Training Calculator Note: Light reflection and differences in display screens may cause slight variations between the color of the item in the photo and the actual product. Measurement tolerances may vary by +/- 1-3 cm.