Inline plastic ball valve, 3/8 inch x 3/8 inch barbs on both sides. Use for stopping the flow of wine or beer in transfer tubing.
Butterfly valves have the distinct advantage over ball valves in that they won't trap wort inside. They are the most sanitary valve you can ask for and are easy to clean in place.
These valves are a direct replacement of the butteryfly valves that come on MB conical fermenters and brite tanks.