MIRA Safety VK-450 Smoke/Carbon Monoxide Filter Cartridges Transform your gas mask into a reliable, fully-functioning, multi-use smoke hood with these VK-450 filters. Designed to overcome smoke & particulates (along with high concentrations of carbon monoxide), these advanced filters can provide crucial hours of protection and clean air from some of the most common disasters faced by US citizens. Proven design provides comprehensive protection from a wide range of NBC threats, smoke and particulates. Smoke respirator mask filter can be used in environments with as little as 17% oxygen.