5x Anti-Fog - Building upon the hydrophilic, micro-etched surface area principles of Smith's Fog-X lenses, the 5X Anti-Fog inner lens has been engineered to provide more than five times the absorptive properties of anything on the market. Initial testing showed standard anti-fog lenses fogging between 30-50 seconds. Smith's proprietary, 5X Anti-Fog treatment withstood fogging for more than 120 seconds in controlled lab tests.