Air Force One "Ballistically Brilliant" airgun chronograph. Fully portable. Rechargeable battery powered. Indoor and outdoor use. Calculates muzzle energy in either ft/lbs or joules with an accuracy of -/+ 1.3%. All data is downloadable to a computer. Back-lit LCD display. Measures temperature and humidity at time of shot. Can record speeds from 49 fps to 2789 fps. Comes with charging and data cables. Measures 105mm x 57mm x 70mm. Weight 230g.