ZSDTRP HSR Air Adjustment Screw for HSR42 HSR45 HSR48 Carburetor Air Screw kit 604-26014 This air adjustment screw is designed for use with HSR42, HSR45, and HSR48 carburetors.It replaces 604-26014 and functions as the air mixture screw to help regulate airflow into the carburetor.The kit includes the air screw and a spring, providing all necessary components for installation.Made from materials, it supports proper carburetor performance and idle mixture tuning.This replacement part is intended for use during carburetor maintenance or rebuilds.