Simplex, der cooling tube for fast and flexible cooling. Made out of high quality V4A stainless steel spiral tubing for efficient heat transfer. Unlike conventional corrugated pipes, the smoother shape of the (spirally-shaped) surface improves heat transfer and cleaning. For one thing, no water pockets form in the flowing cold water inside, and for another, the fermenting material cannot collect between the corrugations outside. Simply insert in the bunghole and connect with cold water. An additional hole in the silicone bung allows for an air lock.