This is an authentic Subaru/Robin replacement part, sourced from the original manufacturer for use with small engines. The main jet is used within the carburetor float bowl chamber. Over time fuel passages in the carburetor can clog and can prevent fuel from moving freely. Repairing or rebuilding a clogged carburetor can improve the engin...Read moree's performance and can save the carb. This main jet is available as an individual replacement part, please see model diagram for associative parts.