The 3/8"Tube X 3/8"Tube Brass Prestolok Union Fitting is .625" outside diameter and 1.66" long with a .312" diameter flow. Materials of construction are nickel plated brass bodies, nitrile O-rings, polyacetal push buttons and stainless steel grab rings. Recommended tubing is LLDPE, PP, Nylon, and 90 A or 95A polyurethane tubing. Fittings are rated up to 300 PSI depending on tubing. Temperature range is 0°F to 200°F.