Knot Knowledge Air Force Senior Airman Tevin Tolver ties down ropes holding a rib from a maintenance structure on Bagram Airfield, Afghanistan, Feb. 12, 2016. Tolver is a structures airman assigned to the 455th Expeditionary Civil Engineer Squadron. Air Force photo by Capt. Bryan Bouchard SHARE: Download: Full Size (0.54 MB) Credit: Capt. Bryan Bouchard VIRIN: 160212-F-IT298-009C.JPG Photo Gallery