Fibre-Metal Faceshield Wide View Windows Are Injection Molded From Propionate, Which Is Superior To Other Window Materials In Every Major Performance Characteristic. They Are Preformed At The Factory To The Exact Curve Specified Crown Protectors For Easy Installation An Exact Fit And A Perfect Seal Against Dust, Dirt And Debris. All High-Performance Models Are .060" Thick And Made To Fit F400 And F500 Faceshields.,