We’re offering two FLASH 5.11 Undergear shirts, a short-sleeve crew-neck and a long-sleeve mock-neck. Both shirts feature saddle-shoulder construction. This takes more time and material to produce, but the result is worth it. You’ll find these shirts comfortable – even with all your gear on. In addition to the fire-resistant nature of the FR-x3 fabric, the material is antimicrobial and moisture wicking – for a great combination of comfort and performance.