Heavy-duty ceiling heaters have a white powder coated 18 gauge steel grill. These commercial heaters feature a steel block fin element and an automatic reset thermal limit that de-energizes heaters if over-heating occurs. The fan purge circuit has 2 -wire control circuit for use with a remote wall thermostat (not included). Vane axial fan blade on Heaters with 1500W - 4000W feature 700 RPM motor with 175 CFM; 4800W Heaters have 900 RPM single phase motor with 200 CFM. Ceiling heaters include an easy-to-use disconnect switch. Optional Accessories include: Back Can, Surface Mount Adapter, 2X2 T-Bar Mounting Kit, and a Factory Installed Thermostat (Single Pole, Positive off. Range -60°F-105° Ceiling heaters measure 14-3/16"W x 4D x 19-15/16"H approx. Grill measures 15-3/8"W x 20-1/8"H. UL approved. 1 Year Limited Warranty.