Integra System: One-of-a-kind air/fuel shut-off device offers double protection, Maintenance free – no filter to clean, standard replacement parts. Environmentally friendly burner: Low NOx design for low nitrous oxide emissions. Standard features: Optional base kits for replacement of pre-FVIR units, side inlet temperature and pressure relief valve opening, two hole top for anode rod and hot water outlet, factory installed temperature and pressure relief valve –side location, altitude certification up to 6,000 ft. above sea level, high altitude models available, specially formulated glass lining prevents corrosion and extends the life of the tank, patented R-Foam insulation process for superior heat retention, Piezo ignitor – easy light pilot, no matches required, anode rod equalizes aggressive water action, cold water inlet – side connection allows for quick, economical hook-up, optional leg kit for replacement units. Factory set as natural gas, with burner and conversion instructions to convert to LP. Same thermostat. Adjusts from 4” water column to 11” for LP gas.