The Osburn Matrix Wood Burning Insert Insert is an aesthetically pleasing cast iron wood burning insert. This EPA approved insert packs a lot of heat with style! With an output up to 75,000 BTUs/hour. Each model is equipped with an ultra-quiet crossflow blower. The secondary air pipes are integrated into the 1/8” stainless steel baffle to give rigidity that withstands even the severest conditions and to ensure combustion of the highest quality.