ProCom Dual Fuel Ventless Blue Flame Heater, 30,000 BTU, Model# MNSD300TBA-BB Safety assurance: O.D.S. (Oxygen depletion sensor) included with automatic shut-off Economical: 99.9% efficient, No outside duct or chimney needed Safety assurance: O.D.S. (Oxygen depletion sensor) included with automatic shut-off Heating coverage:- 1000 square feet