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!
The Solo Stove Campfire also features a heat shield between the ash pan and the bottom of the stove. This heat shield protects the ground under the stove from scorching. The cooking ring's angled lip also increases efficiency by directing heat towards your pot minimizing heat loss. It also acts as a windshield while still allowing oxygen to flow inward. The Solo Stove Campfire is indeed one of the most efficient wood burning stoves you'll ever own.