Kit contains 3 of each: Tee, elbow, cross, joiner, with barbed ends. Aquatic micro fittings for connecting standard tubing for air-controlled devices such as airstones, filters, protein skimmers, ornaments, etc. Also for connecting liquid feed lines for metering pumps, fertilizing systems, and drip irrigation of water gardens and paludariums. Fits standard 1/4" OD tubing.