All Kalfire closed wood fires are completely airtight, which makes the strength of the fire easy to adjust. This means you never need to consume more wood than is strictly necessary. To change the level of the fire, a sliding lever modifies the secondary air supplied to the fire to achieve the strength you desire.
Sliding the lever to the right increases the air so the fire burns more strongly; sliding it to the left reduces the air supply so it burns more calmly. This feature gives you complete control over the fire, allowing you to create the atmosphere of your choice.