Due to the built in oxygen safety sensor, vent free products may not work properly at elevations above 4,500 ft. Not for sale in California or Canada. WARNING - CALIFORNIA RESIDENTS ONLY. This product and the fuel used to operate this product (natural gas), and the products of combustion of such fuel, can expose you to chemicals including benzene, which is known to the State of California to cause cancer and reproductive harm.Items must be in new condition, sealed in their original packaging to be eligible for return. Items must have all tags and labels attached, and must show no signs of wear or use. The item "Comfort Glow KWN521 30,000 Btu 5 Plaque Natural Gas Infrared Vent Free Heater" is in sale since Thursday, August 6, 2020. This item is in the category "Home & Garden\Home Improvement\Heating, Cooling & Air\Heating & Cooling Appliances\Space Heaters". The seller is "comforthome82" and is located in Petersburg, Pennsylvania. This item can be shipped to United States.