stainless steel and zinc plated carbon steel, Oetiker® ear type clamps breathe to adapt to expansion and contraction while remaining secure and tamper-proof. Stainless steel worm gear clamps, also available, install by screwdriver tightening. Lined version is available for use with very soft tubing. Manufactured from UL-listed black nylon 6-6, Kwik Clamps(TM) will not rust or corrode and are non-conductive. Double row of teeth ensures bond that will not vibrate loose