Galvanized steel, square-locked core with a continous copper ground wire built into the core from 3/8" to 1-1/4", interlocked core from 1-1/2" to 4" to give additional strengh to prevent unravelling, grounding must be installed externally. Conform to UL requirement. Smooth wipe clean PVC jacketed Liquid-tight IP66/IP67  Good flexibility High mechanical strength Flame retardent UV protection moisture proof Resistance to most of chemicals, such as oil, acids and vapours, etc. Good Absorption of motion and vibration Cover does not winkle when bent  Temperature range from -15^oC to +105^oC PVC colour black (standard), grey or orange (made to order) Nickel plated brass fittings Galvanized malleable iron fittings Stainless steel fittings