For reliable, intuitive aviation calculations - batteries not required - ASA's compact, Circular Flight Computer is just the item for all your flight-planning needs. Compact and lightweight at just 6" (diameter) and 0.7 lbs, this colorful whiz wheel will serve you well in even the tightest of cockpit configurations. The calculator side makes it a cinch to perform time, speed, and distance calculations; determine fuel consumption; convert between units of measurement; compensate for the effects of ambient temperature and pressure; and much more. Flip the device over and the wind side allows you to determine your crosswind component, wind correction angle, groundspeed, and a host of other need-to-know performance parameters. Its matte finish allows you to mark on it with a pencil and easily wipe away when you're done. It's also approved for use of FAA knowledge tests. A compact, affordable, proven tool that should be a "no-go" item in every pilot's flight bag.