This is the O.S. T-Series RP7 Cold Heat Range Turbo Glow Plug. FEATURES: T-series glow plugs are ideal for racing car engines that create high RPM For .12, .15 and .21 size turbo head on-road racing engines Ideal plug for any outside temperature INCLUDES: O.S. T-Series RP6 Cold Heat Range Turbo Glow Plug REQUIRES: Glow Plug Wrench, HCAP2550 COMMENTS: This glow plug is different from the conventional glow plug. It is made to fit the inner head of engines with a turbo-type cylinder head design. jxs 2/27/09 ir/jxs