CONDUCTOR 19 strands of 0.25mm tinned copper cor (1mm sq nom). for electrode gap refer to makers manual first install plugs finger tight then tighten with a plug spanner. They have a waterproof seal around the spark plug and are resistant to oil, water and under-bonnet corrosive materials.Ignition leads connect the distributor to the spark plugs and therefore form an important part of the overall car engine ignition system.