CALORITECH GX Series Heavy-Duty Forced Air Unit Heaters are specifically engineered for heavy-duty use in industrial environments, such as mine shafts, pulp and paper mills, hoist houses, welding shops, maintenance shops, sewage treatment plants, chemical plants, weigh scale pits, elevator shafts, crane cabs and more. The heavy-duty construction of this heater will reduce the downtime and maintenance costs associated with standard-design heaters. Specifically Designed for Application in Non-Hazardous Environments: - Mine shafts- Pulp and paper mills- Hoist houses- Welding shops- Maintenance shops- Sewage treatment plants- Chemical plants- Repair shops- Wash down areas- Weigh scale pits- Elevator shafts- High humidity areas- Crane cabs. Color: Gray.