This is the P5 Turbo Off-Road Very Hot Glow Plug from O.S. Engines.
FEATURES: Very hot plug for turbo cylinder head engines such as the O.S .21 VZ-B V-Spec and most .18 -.28 cu in (2.9 - 4.6 cc)...
This is the P4 Turbo Glow Plug for use in the OS Max .21VZ-B VSPEC and .21VZ-B Speed Tuned Engines.
FEATURES: For use with fuel containing 25% or greater nitromethane content Also works well