* Ease of installation - fits standard mobile home furnace footprint* Easy conversion from natural gas to propane - all models have convertible gas valves* A/C ready up to 4 tons* 4-speed blower * Lifetime heat exchanger warranty* ETL Listed* Sealed combustion design draws combustion air from outside* 18 gauge aluminum coated primary heat exchanger & 24C stainless steel secondary heat exchanger provide long life