The Milvent Protective Vents far outperforms a waterproof vent for keeping small enclosures very dry; optics and electronics are kept drier because the valve is normally closed to both water and water vapor, which allows it to be used with desiccant. By contrast, a waterproof vent is always open to water vapor.
The Milvent Protective Vents provides the same protection and performance as a traditional spring-actuated breather valve, but at less cost, and in a smaller, lighter package