Grand Theft Reactive Coverstock. Finish: 500/1000/2000 Abralon. High Mass Bias Gas Mask w/Flip Block Core. 16# RG 2. 51 Diff 0. 049. 15# RG 2. 50 Diff 0. 060. 14# RG 2. 49 Diff 0. 057. Mass Bias 0. 016.