U.S. Army Spc. Zachary Segraves, assigned to Charlie Company, 426th Brigade Support Battalion, 1st Brigade Combat Team, 101st Airborne Division, applies a Tegaderm dressing over a saline lock during a mass casualty exercise on Jalalabad Airfield, Nangarhar province, Afghanistan, May 12, 2013. The mass casualty exercise is an event where soldiers demonstrate their medical knowledge in a controlled environment and are evaluated on their performance. (U.S. Army photo by Spc. Vang Seng Thao/Released)