iEvac E500 Industrial Escape Hood is NIOSH Certified for a wide range of Toxic Industrial Gases, especially H2S, Vapors and Particulates. No maintenance or fit test required. Longer protection time. The hood is reusable with a single easily replaceable filter using a universal connection, with a 10-year shelf life. Smaller, lighter, faster and easier to use. Will save you Thousands of Dollars Compared to Escape Bottles.