I bought my barrel kits from Vogelzang Inc 1-800-222-6950
The units that I bought are the Model BK150E Deluxe Barrel Stove Kit. Features include a large, well fitting, gasket, feed door. A separate gasket ash clean out door engineered for “easy clean” ash removal. A “cool touch” cam-lock type door latch and a counter weighted spin dial draft control. The Model BK50E Double Barrel Adaptor Kit does just what it says. Mounts the second barrel on top. I also had to order two more damper collars. One for the extra vent from the fire chamber to the cook chamber, and the other for the outlet on the cook chamber. All of the dampers are 6 inches in diameter, which is fine for moving heat to the cook chamber but bad for holding heat in. The damper on the cook chamber works great at stopping the heat loss. Don't worry to much about this stuff. You'll get to see it in the construction phase.