Needle JetInside diameter increases in size as size?s code increases alphabetically and numericallyGenuine Mikuni needle jets will have series and size stamping for identificationNeedle jets allow a great way for tuning carb at 1/4-3/4 turn throttleMade in JapanFits Mikuni VM38 SpigotFeatures: For VM38 mm Spigot Units: Each Type: Needle Jet Size: P-0 Model: Type 166 Product Name: Jet Material: Brass