"Single-ply, helically corrugated stainless steel alloy wall hose construction with a four-ply finished seam that is folded flat and crimped for tightness and strength. " Light weight and hand bendable and self supporting to form elbows and turns easily during installation. Designed for extreme temperature application. Resists metal fatigue, weathering, and most corrosive fumes & chemicals. Not recommended for continuous flexing.