LRP WT4 medium hot turbo glow plug for nitro RC engines.
This is one of the best Turbo plugs available these day with better quality than most others out there since everyone got cheap with there plugs but not LRP!
 
This glow plug is a great plug for most all nitro engine including Picco, Novarossi, Werks, Nova, LRP, and OS.   A great plug for Turbo head .21 to .32 engines.