On our way to the Topeka KS Mother Earth News Fair we stopped by to see our friend Sky and see the latest innovations. The Liberator is unique in that it is (as of early 2020) the only UL Listed Rocket Heater sold in the US. It also burns wood scraps or pellets (without needing electricity) and plugs into a thermal mass battery bench to make a Rocket Mass Heater. The video shows a lot of exciting upgrades on the second generation Liberator that improve efficiency (and probably longevity, though the first generation Liberators are still going strong. No burnout has been reported and mine is working great). You can find more at https://www.rocketheater.com/ If you decide to buy one Sky will give you $100 off if you tell him "Uncle Mud Sent Me".