ELLSWORTH AIR FORCE BASE, S.D. — (Left) Staff Sgt. Darryl Wilcken, 28th Civil Engineer Squadron explosive ordnance disposal journeyman, observes as (right) Tech. Sgt. Jayson Wells, 28th CES explosive ordnance disposal journeyman, ties a knot, March 30. The knots are branched from the main line which, once triggered, will set off a shaped charge. (U.S. Air Force photo/Senior Airman Adam Grant)