Osburn 3500 Wood Insert w/ 5.5" x 25' Forever Flex Liner Kit OB03510KOsburn 3500 Wood Insert w 5. 5" x 25' Forever Flex Liner Kit OB03510K Review Do you desire a magnificent fireplace insert that heats your room effectively and beautifully? You may get the Osburn 3500 Wood Insert with 5. 5" x 25' Forever Flex Liner Kit OB03510K! The Osburn 3500 wood insert combines power, efficiency, and safety. With its amazing features and sober lines that give way to one of the largest glass surfaces in its category, this insert