When the air is dangerous to breathe, your mask needs filters that won’t fail. Our MIRA NBC-77 SOF 40 mm filters offer certified protection across the full spectrum of CBRN threats, from nerve agents to radioactive iodine. With ratings like A2B2E2K2HgSXP3 D R., these filters are built tough to endure rough use and backed by a 20-year shelf life. Shop filters that fit standard NATO-threaded gas masks and offer breathable protection that lasts for decades.