C 1 Emergency Sustenance Vest. I won it for $213USD from bidding in Engineered Garments Men's C 1 Vest in Dark Navy Feather Twill 40s USAF Type C 1 Vest 1940's US.ARMY AIR FORCES C 1 VEST LEAD 40s us army air force c1 vest. The C 1 Vest is a versatile, mid weight piece made from a durable cotton poly twill fabric, designed for a standard fit. Crafted in the USA, it features a V neckline, front button and tie closure, angled flap cargo pockets on the chest and waist, a lower back cargo pocket, and a unique back cut out with self tie fastenings. Perfect for layering or adding an extra edge to your look.