50 Gallon, Natural Gas, Ultra Low Nox Water Heater, 40,000 BTU's, Draft Diverter Outlet Size 3" With Integrated Adapter For 4" Vent Option, .60 Energy Factor, Recovery At A 90 Degrees Rise-Gallons/Hours 43, First Hour Rating 91,1" 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 60-3/4"H x 20"D, BAAQMD Regulation 9 Rule 6, YSAQMD Rule 2.37 SMAQMD Rule 414 & SJVAPCD Rule 4902, D Rated Sea Level To 7,700, Meets New NAECA 2015 Efficiency Standards.