Duraflame 6lb 4-hour Firelogs. Fast lighting - lights fully in less than 5 min. Duraflame firelogs light faster and burn more completely than firewood, and because far less material is consumed when burning a firelog, significantly fewer pollutants are emitted than a comparable wood fire. Robust flames that last up to four hours. Lights quickly – full flames in less than 5 minutes. Use in an indoor, open hearth fireplace or outdoor fireplace or fire pit. Burns 80% cleaner than wood. UL approved safety classification for use in UL-listed factory built fireplaces. Chimney Safety Institute of America Accepted Product.