The HD Line of portable, multi-fuel, forced-air heaters come equipped with heavy-duty high-output fans, beefed-up handles, 10-in. pneumatic tires, large-capacity fuel tanks and a range of sizes. Seven models consist of two compact units (50,000 and 75,000 BTU/hour), three wheeled units (125,000, 175,000 and 210,000 BTU/hour) and two large direct-fired heaters (360,000 and 610,000 BTU/hour) with the power to heat up to 114,000 sq. ft. All models operate using kerosene, No.1 or No. 2 diesel, JP8 or Jet A fuel, and will operate in sub-zero temperatures.