Depleted uranium (DU; also referred to in the past as Q-metal, depletalloy or D-38) is uranium with a lower content of the fissile isotope U-235 than natural uranium. (Natural uranium is about 99.27% U-238, 0.72% U-235—the fissile isotope, and 0.0055% U-234). Uses of DU take advantage of its very high density of 19.1 g/cm3 (68.4% denser than lead). Civilian uses include counterweights in aircraft, radiation shielding in medical radiation therapy and industrial radiography equipment and containers used to transport radioactive materials. Military uses include defensive armor plating and armor-piercing projectiles.