Staff Sgt. Brian Elrod, 436th Logistics Readiness Squadron fuels laboratory noncommissioned officer in charge, looks through a refractometer to inspect the water content from a fuel sample at Dover Air Force Base, Delaware, Jan. 12, 2021. The refractometer measures the effectiveness of additives by separating water in the fuel. (U.S. Air Force photo by Airman 1st Class Stephani Barge)