A memorial is displayed during the 7th annual 9/11 fire climb by the Okie firefighters from the 507th Civil Engineer Squadron Sept. 11, 2016, at Tinker Air Force Base, Okla. Each year, Reservists climb up and down the fire-training tower to complete the 18 laps within 56 minutes, the amount of time it took the South Tower of the World Trade Center to collapse. (U.S. Air Force photo/Master Sgt. Grady Epperly)

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Photo by: Master Sgt. Grady Epperly |  VIRIN: 160911-F-YA646-0003.JPG