Penn Plax air equipment airline tubing is made from a durable, flexible silicone material that allows it to endure for longer than most other airline tubing options. Unlike non-silicone airline tubing, Penn Plax Deluxe Airline Tubing (Penn Plax STD200) won't harden or crack over time, so you can install it in the most demanding aquarium environments and expect it to withstand for longer. This flexible material also allows the tubing to stay soft and flexible without kinking, so it's easier to work with and maintain in your air pumps, aerating ornaments and accessories. It comes in a standard 0.187-inch tubing diameter and can be ordered in whatever length you need. Penn Plax Airline Tubing is sold by the foot to ensure that you get the proper amount for your custom build or replacement. Simply indicate the number of feet in the quantity drop-down menu and then check out as usual.