Members assigned to the 4th Civil Engineer Squadron Explosive Ordnance Disposal team build a coffer dam around thermite grenades at Seymour Johnson Air Force Base, North Carolina, May 14, 2020. A coffer dam is made to keep the slag from the grenades in a concentrated area over the metal, improving the effectiveness of the thermite grenade. (U.S. Air Force photo by Senior Airman Jacob Derry)