For Mildot and Ballistic Plex Reticles - An easy way to figure out the range to each aiming point on a ballistic reticle. Plug in your bullet weight, sight height, muzzle velocity, and ballistic coefficient... The results display on screen. You can print out the reticle data to tape on the side of your scope. For Windows XP Operating System and NOW works with Vista and Windows 7 too!