Paulson's DK5-H.150HM face shield has a hard mount system designed to fit any PASGT helmet and is 4,2mm thick.This item is NIJ 0104.02 & MIL-V-43511C & USA NSN 4240-01-430-1983 Certified. Certificate #C3305PMC Issued by DINCERTCO, Aalen, Germany Standard EN166