The MIRA Safety NBC-77 SOF is a 40mm NATO-threaded CBRN gas mask filter rated A2B2E2K2HgSXP3 D R REACTOR under EN 14387:2004+A1:2008 and DIN 58621:2011. Manufactured in the Czech Republic, it pairs with any compatible full-face respirator or PAPR to protect against all known CBRN agents, toxic industrial chemicals (TICs), radioactive iodine and its organic compounds (including methyliodide-131), and hazardous particulates. The filter weighs 335 g (±5%), measures 110 mm in diameter and 85 mm in height, and carries a 20-year sealed shelf life. Available in Black, Ranger Green, and Sandstone — all identical in performance and specifications.

Who this is for

• Emergency preparedness households: anyone building a serious emergency kit who wants a single filter that covers CBRN agents, industrial chemical exposure, and radioactive iodine without stocking multiple cartridge types.
• CBRN and special operations professionals: military, law enforcement, and first-responder personnel who require a filter tested and rated as a Reactor filter and certified under EN 14387 for the broadest threat coverage available in a 40mm canister.
• Industrial and hazmat workers: personnel operating in environments with organic/inorganic acid fumes, ammonia, mercury vapors, organic solvents, or other toxic industrial chemicals requiring combined-filter protection rated to A2B2E2K2Hg standards.

Ballistic performance

This section does not apply to a gas mask filter. See Threat coverage below.

Threat coverage

The NBC-77 SOF carries a combined filter rating of A2B2E2K2HgSXP3 D R REACTOR — one of the broadest ratings available in a consumer-accessible 40mm canister. Breaking that down: A2 covers organic gases and vapors; B2 covers inorganic gases and vapors; E2 covers acid gases and vapors; K2 covers ammonia and amines; Hg covers mercury vapors; SX covers specific named warfare agents including cyanogen chloride (CK), chloropicrin (PS), and phosgene (CG); P3 is the highest particle filtration class, blocking more than 99.999% of particulates at 95 l/min flow; D confirms resistance to clogging by dolomite dust; R confirms the filter is reusable (not single-use); and REACTOR confirms it filters radioactive iodine and organic iodine compounds (methyliodide-131) per DIN 58621:2011.

The P3 particle layer also provides protection against solid and liquid aerosol particulates including bacteria, fungi, viruses, toxins, radioactive particles, smoke-producing substances, and riot control agent particulates. Unlike the SX-rated category, virus and pathogen filtration is a function of the P3 layer, not the activated carbon bed.

The NBC-77 SOF does not protect against carbon monoxide or nitrogen oxides. For CO-producing environments such as smoke and fire, the VK-530 is the appropriate filter.

Independent test data

All breakthrough times tested at 70% relative humidity and 30 l/min flow rate per EN 14387+A1. Particle filtration efficiency exceeds 99.999% for both sodium chloride (NaCl) and paraffin oil aerosols at 95 l/min — well above the EN 99.95% minimum requirement.

Compatibility and thread standard

The NBC-77 SOF uses an Rd 40 × 1/7" thread per STANAG 4155 (EN 148-1) — the NATO standard 40mm configuration shared by the vast majority of modern military, law enforcement, and civilian full-face respirators. Confirmed compatible masks include the MSA Millennium, Scott M110, Avon C50, Israeli civilian gas masks, Polish MC-1 (verify threading variant before ordering), and MIRA Safety CM-6M and CM-7M platforms, among others. It will not fit Soviet/Russian 40mm GOST-threaded masks such as the GP-5, nor is it compatible with dual-cartridge half-face respirators using proprietary bayonet or 40mm-incompatible ports (such as the North by Honeywell 5400 Series).

Construction and housing

The canister housing is hard plastic, engineered to resist shock and impact in field conditions. The P3 particle layer incorporates a hydrophobic coating that repels water during decontamination showers, heavy rain, and heavy snow — the filter remains functional under wet conditions. The NBC-77 SOF is not rated for full submersion and should not be deliberately submerged.

Storage, service life, and disposal

Each filter ships factory-sealed in a plastic bag. Store sealed units in a clean, stable environment between -5 °C and +30 °C at relative humidity below 80%. Sealed filters tolerate a wider range of -30 °C to +50 °C at up to 95% relative humidity. The storage period (month and year) is marked on the filter label. Sealed shelf life is 20 years.

Once opened and used in a contaminated environment, the filter is considered hazardous waste. Do not attempt to regenerate a used filter. Do not clean filters with compressed air or water. Dispose of used filters according to local hazardous waste regulations for the substances filtered.

Specifications

Frequently asked questions

What does the REACTOR rating mean?

REACTOR indicates the filter has been tested and rated to filter radioactive iodine and its organic compounds — specifically methyliodide-131 — per DIN 58621:2011. This is relevant in nuclear incident scenarios such as dirty bombs or reactor accidents where radioactive iodine gas may be released. The NBC-77 SOF exceeds the 2-hour minimum breakthrough time required by the European standard at the tested concentration.

Will this filter stop nerve agents, blister agents, and other chemical warfare agents?

Yes. The combined A2B2E2K2HgSX rating covers the full spectrum of known CBRN warfare agents, including G-agents (sarin/GB, soman/GD, tabun/GA, cyclosarin/GF), V-agents (VX, VR, VE, VG), blister agents (mustard gas/HD, lewisite/L, phosgene oxime/CX), blood agents (hydrogen cyanide/AC, cyanogen chloride/CK), and choking agents (phosgene/CG, diphosgene/DP, chloropicrin/PS), among others.

Does this filter protect against smoke and carbon monoxide?

No. The NBC-77 SOF does not cover carbon monoxide (CO) or nitrogen oxides. For fire-smoke and CO environments, the VK-530 Smoke Filter is the correct choice, as it includes an oxidizing agent that converts CO to CO2.

How long does the filter last once opened and in use?

It depends on the contaminant, its concentration, and your breathing rate. Breakthrough time is calculated as T = DAC × 1,000 / (airflow × concentration). The technical data table above lists DAC values and breakthrough times for each rated agent at 5,000 ppm and 30 l/min. For emergency evacuation purposes, plan for two filters per person per day as a conservative baseline.

Will this fit my gas mask?

It fits any mask threaded for 40mm NATO (Rd 40 × 1/7" per STANAG 4155). Confirmed fits include MSA Millennium, Avon C50, Scott M110, and most modern military and civilian full-face respirators. It does not fit Soviet GOST-threaded masks (such as the GP-5) or dual-cartridge half-face respirators with proprietary ports. If you are unsure whether your mask is 40mm NATO threaded, contact us before ordering.

Can this be shipped to my state, and are there any purchase restrictions?

Gas mask filters are legal to purchase in all 50 U.S. states for civilian use. They are subject to U.S. export regulations — international buyers should confirm import permissibility in their country. Under 18 U.S.C. § 931, anyone with a federal felony conviction for a crime of violence is prohibited from purchasing or possessing body armor; that statute does not apply to gas mask filters, which carry no equivalent federal restriction.