CSST
Corrugated stainless steel tubing is tubing made of stainless steel with corrugation on the inside or outside. CSST is not FAC tubing. Presently, CSST and FAC tubing both use corrugated stainless steel tubing. In the past, FAC used corrugated brass tubing. However, FAC tubing is made only in lengths of 1 to 6 feet, FAC tubing is made with connectors on each end, and FAC tubing does not have a plastic sheath. On FAC tubing the corrugations are visible. CSST's plastic sheath covers its corrugations.