Low-profile frame, two-piece strap w/Snap-On/Snap-Off mounting brackets. The ESS FirePro-1977 Series includes the most advanced low-profile willdand fire and rescue goggles on the market. The compact frame design prevents helmet interference while increasing peripheral vision. The FirePro-1977 is certified to meet the NFPA 1977 wildland fire equipment performance requirements, including the 350F for 5-minute oven test. They are also U.S. Federal OSHA compliant, exceed the requirements of ANSI Z87.1-2010, and are considered Primary Eye Protection by NFPA 1500.