YOUR ADVANTAGES WITH AIRBOSS. NATO’s lightest mask, the C4 is a negative-pressure, full-face respirator with an ergonomic butyl face piece designed for challenging operations and activities. Easy to Don & Doff. With its stretch-fabric head harness and two simple adjustment pull straps, the C4 respirator is easily donned and doffed. The mask’s non-fogging, fragmentation-proof polycarbonate lenses provide outstanding peripheral and ground visibility. Provides excellent protection against CW agents and TICs when used with an appropriate filter; impermeable to all biological agents. Excellent protection against a wide range of TICs. (list available upon request). 45°C to 70°C (-49°F to 158°F). 55°C to 60°C (-67°F to 140°F). 15 years in original package if properly stored. Black (also available in olive green or tan for large orders). 440 g (1 lb) per unit (size M). Vacuumed foil bag (3000 cm3).