It depends on your ignition system condition and your type of vehicle., copper wont last as long as platinum or iridium but they are cheap and get the job done but end up costing the same if not more in the long run. I run auto lite 104's but will eventually change to ngk's because in tired of changing them. My old lesabre used to chew up platinums like they were gas because of the dis ignition was too much i guess.