United States Marine Critical Skills Operators with 1st Marine Special Operations Battalion, Marine Corps Forces, Special Operations Command prepare to execute their final jump of a double-bag static line (DBSL) parachute training course, Aug 29, 2014, in rural Arizona. The DBSL course was an introduction to the High Altitude, High Opening (HAHO) insertion method utilized by Special Operations Forces. (U.S. Marine Corps Photo by Lance Cpl. Steven M. Fox/Released)