Plastic tubes are long hollow cylinders that hold or transfer liquids, gasses, or are used to hold and protect wires and cords. Acrylic tubes are scratch-resistant and have the same clarity and brilliance of glass, but are lighter and more durable. UHMW polyethylene tubes are strong and impact-resistant. They are easy to thermoform and have a slippery surface that resists sticking and binding. PVC tubes are strong, stiff, and easy to thermoform. They are excellent insulators and are used to protect wires and other materials that can be slid through them. Polycarbonate tubes offer excellent impact resistance and are easy to machine. They are commonly used to make instrument gauge covers and display racks.