Charking 2 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. Classified ul. Processed solid fuel classified for use in factory-built fireplaces 7l47. For united states, this firelog has been tested by underwriters laboratories inc. For use in factory-built fireplaces. For canada, this firelog has been designed for brick or heavy gauge metal lined masonry fireplaces, ul or cul or ulc listed fireplaces, space heaters, and fireplace inserts having minimum burning areas of 400 sq. In. (0-258Sq.M.). Use in smaller appliances may be hazardous. Unconditionally guaranteed.