Made from food grade PVC Blends in with background Very flexible and kink free Start off your next aquarium with this deluxe aquarium airline tubing in black. The black tubing helps blend in with live plants and backgrounds to give your fish tank a cleaner look. We tested many types of airline tubing before choosing this type due to it being the most premium we could find. It remains flexible longer than other types of airline tubing.  Material: Food grade 1/4 inch PVC tubing Sizes: 10-foot length, 25-foot length, and 300-foot spool Directions: Measure out the length of airline tubing and use scissors to cut it perpendicular to the line so that it has a flat edge. Insert the device (e.g., check valve, air pump, or sponge filter) as far up the airline tubing as possible for a tight fit.  Note: All airline tubing eventually hardens when left in water for long periods of time. If you are unable to reattach your device because of hardened airline tubing, cut off 0.5–1 inch of the affected section and it will be more pliable to reattach. In the case of a sponge filter, try to leave the airline tubing connected to the plastic top and remove the filter base in order to access the sponge for cleaning.