This is the ProTek R/C O.S. P3 "Ultra Hot" Turbo Glow Plug, the exclusive plug of the Samurai 321B Nitro Engine. The ProTek R/C P3 plug is designed for use in most .18 - .28 off-road turbo head engines such as O.S., RB, Novarossi, Werks and Orion. This...