This is a Bosch iridium/platinum spark plug similar to the ones used in my Scion:
http://ecx.images-amazon.com/images/I/31siZsBbVoL._SL500_AA300_.jpg They are good for about 100,000 miles. They are required replacements in order to meet the California emissions standards. The deep threads are required to reach through the aluminum head. Now what is so special about iridium/platinum? Dunno. But, the use of a spark was mentioned earlier regarding the Langmuir torch. The spark will provide energy to dissociate the H2 molecule providing an rapid source of atomic H. You can figure the rest out yourselves. T
