MADE IN THE USA!!!! SRT piston - Sonic Recharge Technology piston - plated aluminum piston that produces an industry leading recharge rate and virtually eliminates reg shoot down SPA - Shim Pressure Adjustment - change output pressure by adding or removing shims, not springs or pistons MFV - Mini Fill Valve - Non wrist digging, low profile design fill valve Brass or optional Aluminum bonnet - see regulator parts for details Meets all DOT, CGA and ASTM specifications Completely rebuildable by the end user Every regulator is hand crafted and factory tested Super low response curve 0-50 psi from full to emptySafety ASTM COMPLIANT bonnet thread ASTM COMPLIANT DOT burst disc ASTM COMPLIANT Low pressure burst disk ASTM COMPLIANT Restrictor, bleed hole and safety groove Mini Fill Valve IS hardened, plated 5000 psi rated Reg installed to ASTM specifications Product Features50 cubic inch 4500 psi D.O.T. and TC approved Carbon fiber bottle 5 year hydro 8 3/4 inches long x 4 1/2 inches diameter - 1 3/8 inches bottle to ASA Gives you 900 shots per fill depending on marker Brass bonnet system weighs (approximately) 2 lbs 3 oz