40 gallon, natural gas, ultra low nox water heater. 40,000 btu's, draft diverter outlet size 3" with integrated adapter for 4" vent option, .62 energy factor, 1" insulation, factory installed t&p valve new advanced gas control system incorporates an internal microprocessor providing enhanced operating parameters & a tighter differential for precise sensing & faster heating response to optimize performance, valve is self-powered uses a thermopile to generate the power needed to operate valve & incorporates self diagnostics & monitoring, 6 year tank & parts warranty, unit dimensions 62" tall x 18" diameter, baaqmd regulation 9 rule 6, ysaqmd rule 2.37 smaqmd rule 414 & sjvapcd rule 4902, d rated sea level 0 to 7,700’, meets new naeca 2015 efficiency standards.