Rocker box securing bolt, long + washer. Suits ES2, Model 18 1948- 1954 iron heads. ZP, 7 required. 5/16" x 26tpi BSCOriginal Norton part number:8912; A3/108 - rocker box securing bolt; C3/108; 13885; 19843 - rocker box securing bolt, long.8912; A3/108 - rocker box securing bolt