The SI Line (Standard Issue) is designed exclusively for our military and government customers. It is not available in retail stores. Military and government protective eyewear has special requirements. Oakley addresses these unique requirements with all of the products below. Oakley lenses exceed US Government ANSI Z87.1 standards for impact resistance, optical clarity and UV protection. The M Frame 2.0 also meets Mil Spec Standard, MIL-PRF-31013