Heat N Glo model CFX-IN natural gas direct vent insert - special high temp refractory firebox / shell for maximum radiant heat without need for a blower. 35,000 BTU input SIT manual valve with 30 % turn down. Ceramic Logs and stainless pan style burner. Unit has been checked over by gas technician to confirm it works. Comes with secondary bifold brass trimmed glass doors (over top of Robax firebox glass) that open for maximum heat. Minimum fireplace opening size 31W x 21 1/2" H x 14"D - Maximum fireplace opening 39"W x 30"H. Call Alen @ (807) 473-7922