The O.S. LC4 T-Maxx/Revo Plug Medium Glow Plug is ideal for 1/10 scale off road engines such as the Traxxas TRX2.5 and 3.3T engines and the O.S. .21 TMs. It's platinum-alloy coil holds heat without an idle bar and reduces heat-related failures. Like all O.S. Max glow plugs, the LC4 is tough enough to take the heat and provide hassle-free starts and outstanding durability. The LC4's longer reach extends coil farther into the engine's combustion chamber improving combustion for better idling and good acceleration throughout the throttle range. Medium heat range for fuels with 10%-20% nitro content.