It requires no duct work or other venting and includes a built in oxygen depletion sensor! The sleek design and neutral color fits any decor. 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. New Smart Select knob provides easier, faster installation.WARNING - CALIFORNIA RESIDENTS ONLY: This product and the fuel used to operate this product (liquid propane), 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. The item "Comfort KWD259 Blue Flame Propane(LP)& Natural Gas(NG) Vent Free Wall Heater" is in sale since Wednesday, December 2, 2020. This item is in the category "Home & Garden\Home Improvement\Heating, Cooling & Air\Heating & Cooling Appliances\Space Heaters". The seller is "ebuildersmerchant-sales" and is located in Jacksonville, Florida. This item can be shipped to United States.