Staff Sgt. Michael Gwin, 28th Security Forces Squadron military working dog handler, directs his dog, Rex, to search the truck of a car during a random vehicle inspection on Ellsworth Air Force Base, S.D., April 25, 2013. 28th SFS members conduct random vehicle inspections to ensure illegal substances. (U.S. Air Force photo by Airman 1st Class Alystria Maurer/Released)