The air intake holes on the bottom of the stove channels air to the bottom of the fire while at the same time, channels warm air up between the walls of the stove. This burst of preheated oxygen feeding back into the firebox through the smaller holes at the top of the stove causes a secondary combustion. This allows the fire to burn more complete which is why there is very little smoke during full burn. A more efficient burn also means you'll use much less wood compared to an open camp fire. The Solo Stove Campfire doesn't just burn wood. It actually cooks the smoke out of the wood and then burns the smoke not once, but twice! 7 in Wide x 9.25 in High.