Jeppesen CR Computers do everything and much more than the E6B style computers. The CR assists pilots and navigators in everything from solving wind triangles, to polar grid navigation and pressure pattern flying. The CR2 is versatile and solidly constructed to make it a reliable choice. Includes an instruction manual and vinyl carry case.  CR-2 is 4 1/4-inch diameter and CR-3 is 6 inch diameter.   . Solves high- and low-speed problems. Automatically compensates for temperature rise. Takes compressibility factors into account. CR-2 will fit in most uniform shirt pockets.