The flexible inner core is made from a spiral-wound strip of heavy gauge, corrosion-resistant, hot-dipped galvanized steel. The 3/8” through 1-1/4” trade sizes are squarelock formed and include an integral bonding strip of copper that is enclosed within the convolutions throughout the entire length. The 1-1/2” through 2” are designed with a fully interlocked strip. The outer flexible PVC jacket is made from an FDA-approved compound formulated for “Splash Zone” food and beverage contact per FDA CFR21 and NSF 51/61 requirements.