Proform BB1902 calibration spring. Features medium spring, 50-450 lbs range, steel construction, natural finish, ensures accurate valve spring tester calibration, sold as each.
Proform BB1903 calibration spring. Features light spring, 10-190 lbs range, steel construction, natural finish, ensures accurate valve spring tester calibration, sold as each.
Proform BB1901 calibration spring kit. Features heavy/medium/light springs, steel construction, natural finish, ensures accurate valve spring tester calibration, sold as a kit.