Charking 3 hour† fire log burns cleaner than wood*: up to 75% less particulate matter*; up to 80% less carbon monoxide*. Unconditional guarantee - if for any reason you are not completely satisfied by your purchase, simply return the product with proof of purchase for a replacement or refund, whichever you prefer. We welcome any comments or questions you may have. *15Th emission inventory conference, new orleans, may 2006. †variations in fireplace and climatic conditions may slightly alter duration of burn. If your fireplace is functioning properly, emissions of this product should be vented outdoors. A properly installed and maintained fireplace and chimney will dramatically reduce the likelihood of combustion by- products entering your home. An inadequate air supply or a downdraft could cause a fireplace malfunction. If you suspect that your unit is not functioning properly, a qualified contractor should be consulted. Variations in fireplace and climatic conditions may slightly alter duration of burn. *15Th emissison inventory conference, new orleans, may 2006. Unconditionally guaranteed. Up to 75% less particulate matter*. Up to 80% less carbon monoxide*.