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 SpigotModel: Type 159 Jet Size: O-8 Units: Each Material: Brass Features: For VM38 mm Spigot Product Name: Jet Type: Needle