Yay, a plastic tube! No, we jest. This is no ordinary plastic tube, but rather a side-lighting fiber optic tube.
This is a pretty neat way to glow up. Light in the fiber optic cable zooms through the core by constantly bouncing off of the edge of the molded plastic, a principle called "total internal reflection" (which also kinda sounds like a very expensive meditation island retreat). When the light pipe doesn't have total reflection, you can get a nifty lighting effect from the light illuminating the plastic tubing.
This tube is 5mm diameter, but is nice and flexible plastic and when lit with a powerful LED, has a nice glowing effect. You can cut it down from 1 meter with diagonal cutters.
Note: This is just the tube, and does not include an emitter LED. You'll also want to grab one of our fiber lights. We've got them in red, green, blue, white, and Adafruit pink!