motorcycle spark plugs 1.with ISO 9001 certification 2.great mechanic electronic ... of spark plugs,such as auto spark plug,motorcycle spark plugs ,mower spark plug and gasoline engine spark plug,electrode spark plugs,multi-ground spark plugs and copper core spark plugs ect ... alumina4.the core electrode was made of gold,platinum,iridium,alloy,copper and nickel.5.superb insulation6.nickel-plated housing ...