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. Unconditionally guaranteed.