The Edelbrock Performance Series Carburetor Calibration Kits include an assortment of metering rods and jets. One pair of metering rod retaining springs and a complete assortment of step-up springs is included with this calibration kit. Includes an assortment of metering rods and jets One pair of metering rod retaining springs and a complete assortment of step-up springs Components and quantities are specifically tailored for each carburetor These kits include an assortment of metering rods and jets, a pair of metering rod retaining springs, and a complete assortment of step-up springs Designed to tune your car to match any engine or track condition.