Black 18 AWG Tinned Copper Wire - 100. Ancor Marine Grade wire products are the longest lasting and most rugged available exceeding UL 1426 ABYC and US Coast Guard Charter boat (CFR Title 46) standards. They are constructed with premium vinyl insulation that is rated at 600V 105 DegreesC dry and 75 DegreesC wet stays flexible even in extreme cold (-40 DegreesF/C) and resists salt water battery acid oil gasoline heat abrasion and ultra-violet radiation. Highest quality ultra flexible (Type 3) tinned copper stranding provides maximum protection against corrosion and electrolysis while resisting fatigue due to vibration and flexing. Wire Gauge: 18 AWG. Nominal O.D. (inches): 7/64. Nominal O.D. (mm): 3.