U.S. Army Reserve Soldiers from the 391st Mobile Augmentation Company (MAC), Boise, Idaho, prepare an inert crater charge during their rotation at the National Training Center (NTC), Fort Irwin, California, January 19, 2019. The 391st took part in the third rotation of NTC for 2019, a training exercise that occurs 11 times per year over the course of 14 days (U.S. Army photo by Sgt. 1st Class Jason Proseus/416th Theater Engineer Command).