U.S. Marine Corps medics can now practice on each other by wearing a "cut suit" that enables patching up realistic looking battlefield wounds. The American military has long used special mannequins, built to allow medics to realistically practice treating battlefield wounds. The mannequins look like real people, have realistic artificial skin and allow trainees to tend to realistic looking wounds, including the need for minor surgery. But the mannequins don't react to treatment the way people do.
The new "cut suit" enables the trainee to get something the mannequin could not provide; a live human being responding realistically to the wound, and the treatment. Troops are coached on how to act during treatment (except for those few who have been wounded, and have memory to rely on.) The trainees in this case are actually sailors, as the U.S. Navy provides medics for marine combat units (and always have, along with lots of other support personnel). The sailor medics live and train with the marines units, the only difference being the use of navy rank insignia on their combat uniforms.