THD Fuel PinMade from 4140 and max hardened. This pin is properly cut, so to give maximum fueling, but not cut too deep to allow slide pin to slip past the O ring. The pin is also cut with a "flat" ramp design, as opposed to the common "progressive" ramps. This gives a much smoother fueling transition and avoids unnecessary smoke. Made from 4140 and max hardened. This pin is properly cut, so to give maximum fueling, but not cut too deep to allow slide pin to slip