Duraflame® fire logs may be burned in all types of open-hearth fireplaces. They are designed to light fast and burn over 2 hours when used according to instructions. Variations in fireplace and climatic conditions may slightly alter duration of burn. Heat content is approximately 42,000 BTU. Burns cleaner than wood: Duraflame® fire logs light faster and burn more completely than firewood, and because far less material is consumed when burning a fire log, significantly fewer pollutants are emitted than a comparable wood fire. 80% less fine particles, 75% less carbon monoxide, 90% less hazardous air pollutants. Saves Trees: Duraflame® fire logs are recycled wood and agricultural fibers, saving valuable natural resources. A Duraflame® fire log consumes 80% less material than a comparable 2-3 hour wood fire, and burning fire logs instead of wood results in significantly fewer trees cut down for use as firewood. America's #1 Fire Log Brand Burns over 2 Hours Fast Lighting Burns Cleaner than Wood Lights Fully in Less than 5 Minutes Duraflame® Fire Logs Are Suitable for Use in UL/C-UL/ULC Listed Factory-Built Fireplaces Duraflame® Fire Logs are Made with Wax and a Blend of Renewable Biomass Fibers