Retired Air Force Tech. Sgt. Chris Ferrell, a former explosive ordnance disposal technician who suffers from post-traumatic stress disorder and traumatic brain injury after combat tours in Afghanistan and Iraq, displays a mask he painted in Hanover, Pa., April 5, 2017. The mask, which bears the initials and dates of death of his teammates, Air Force Tech. Sgts. Tony Campbell and Adam Ginett, is a form of art therapy employed by therapists to help PTSD patients verbalize past traumatic events. It is one of the therapies that will be used at the Air Force's Invisible Wounds clinic scheduled to open at Eglin Air Force Base, Fla., in 2018. Air Force photo by J.M. Eddins Jr.