ELLSWORTH AIR FORCE BASE, S.D. -- (Left to right) Airman 1st Class Michael DiRienzo and Senior Airman Justin Reinwand, 28th munitions Squadron conventional maintenance crew members, attach a tail fin to an inert Guided Bomb Unit-31, Dec. 8. The tail fin adds balance and stability to the GBU-31. (U.S. Air Force photo/Airman 1st Class Anthony Sanchelli)