Food-grade vinyl tubing. Often used with a bottling buckets, bottle fillers, blowoff tubes, and pumping. Not recommended for hot liquids as the tubing will bend and kink, preventing flow. For hot liquids we suggest silicone tubing.
Tubing compatibility measurements are typically ID (Inner Diameter). If a siphon says it needs 5/16″ tubing, that is the inner diameter it requires. OD (Outer Diameter) is typically not as important.