TRIAD BULLPUP CHASSIS FOR BRN-180 UPPER RECEIVER RIFLE FEATURES: 6061 aluminum front trigger housing/receiver 17-4 stainless MIM front trigger with QPQ coating 4140 steel Anti-walk trigger pins x 3 A3 Tactical ambi selector with detent spring and detent 17-4 stainless front trigger linkage with QPQ coating 7075 aluminum transfer bar and rear linkage, bushed with 841 oil-embedded bronze bushings Acetal Delrin guide and trigger actuator 30% fiber-reinforced injection-molded Zytel polymer main chassis housing. 30% fiber-reinforced injection molded 1.50"""" extended butt-plate (rifle only) 4140 steel and 7075 al Mfg: A3 Industries