This is the O.S. Speed P3 Gold High Performance Turbo Glow Plug from O.S. Engines. 24K gold plated to commemorate O.S.'s 80TH anniversary. For use in off-road RC vehicle engines with turbo type cylinder head design such as the O.S. .21VZ-B V-Spec and most .18-.28 off-road engines with turbo cylinder head. Ultra hot heat range for smooth idle and fast acceleration. Tapered seat mates perfectly with cylinder head for a superior seal