We Use Special Purpose Automotive Wire that is Insulated with Chemically Cross-Line Polyethylene, Making it resistant to moisture, most solvents, and Gives it the Ability to Withstand Extreme Temperatures. These Features Make Our Wire Ideal for Engine Compartment Applications Where Higher Heat Resistance is Required. Our Flexible Polyvinyl Chloride (PVC) Tubing is Designed to Meet the Requirements of MIL-I-631, Grades A & B. This Type of Tubing is used in Appliances, Automobiles, Military Wiring Harnesses and Airborne Equipment. Our PVC Tubing is UV Resistant, Flame Retardant, Lead Free with a High Gloss Finish Making it the Perfect Choice for Applications Where a Wide Thermal Range is Required. Additionally Because of the PVC is Much More Smooth, The Task of Pulling the Wires Through the Bars is Easier...A Nice Little ADDED Bonus!!