Staff Sgt. Matthew Auger, 28th Civil Engineer Squadron heating, ventilation, and air conditioning technician, looks through a reflectometer to determine the amount of glycol in the water at the engine shop on Ellsworth Air Force Base, S.D., Oct. 16, 2012. The HVAC shop visited buildings around base to add an antifreeze mixture to winterize the closed water systems in order to prevent water from freezing in the pipes and causing equipment damage during the winter. (U.S. Air Force photo by Airman 1st Class Alystria Maurer/Released)