Attach your tube to two 2-liter bottles and give it a swirl. Watch your vortex spin in the bottle. Cyclone tube is 2 inches long and will be chosen randomly from 4 translucent colors (yellow, green, blue and red). You are buying just the cyclone tube. This is a great educational and fun experiment and activity for school classes, homeschoolers, scouts and any other group. Create a tornado from two 2 liter plastic bottles, water and a colorful plastic connecting tube. Swirling water creates a funnel-shaped vortex as it drains from one bottle to another. You can create different ways to work with it by timing the water draining, using bits of paper or food coloring or lamp oil.