Staff Sgt. Daniel Sandlin, a martial arts instructor trainer with Advanced Infantry Training Battalion, speaks to his students as they watch two instructors grapple during a demonstration, at School of Infantry (East), Camp Geiger, N.C., Oct. 20, 2010. Sandlin and Sgt. Robert Abrantes, who is also an instructor trainer, both participate in mixed martial arts in addition to their responsibilities as Marine Corps leaders and martial arts instructors. - Staff Sgt. Daniel Sandlin, a martial arts instructor trainer with Advanced Infantry Training Battalion, speaks to his students as they watch two instructors grapple during a demonstration, at School of Infantry (East), Camp Geiger, N.C., Oct. 20, 2010. Sandlin and Sgt. Robert Abrantes, who is also an instructor trainer, both participate in mixed martial arts in addition to their responsibilities as Marine Corps leaders and martial arts instructors.