Rocker box securing bolt, long. Suits ES2, Model 18 1938 - 1948 iron heads. ZP, 7 required. 5/16" x 26tpi BSCOriginal part number:8912; A3/108 - rocker box securing boltA3/108; - rocker box securing bolt, long.8913; A3/109 - rocker box securing bolt washer or stud nut washer