Specification: Type: Centrifugal Clutch Color: Black Material: Steel 10 Tooth sprocket. Fits a 420 chain. 19mm metric bore. HD 420 chain clutch and sprocket set for Honda import Gokart and Buggy engines with parallel 19mm engine drive shafts. Fits the wide range of Honda import clone engines used in Gokarts and Buggies normally on 3.5-7HP 170F engine styles.