This item first appears to be a Large sealed iron barrel weighing 500 pounds. The barrel has a hidden catch, which can be found with a successful DC 20 Intelligence (Investigation) check. Releasing the catch unlocks a hatch at one end of the barrel, allowing two Medium or smaller creatures to crawl inside. Ten levers are set in a row at the far end, each in a neutral position, capable of moving either up or down. The apparatus has AC 20, 200 hit points, and a speed of 30 feet (walking or swimming).