Contains 26 blades with thicknesses .005", .006", .007", .008", .009", .010", .011", .012", .013", .014", .015", .016", .017", .018", .019", .020", .021", .022", .023", .024", .025", .026", .027", .028", .029", .030" Equipped with knurled lock-nut, which releases the blades instantly for rapid selection of size desired and when tightened, locks the individual blade into the working position, retaining the blades not in use firmly to handle 4" long blades have 1" 45? offset for checking valve clearances Made in the U.S.A.. FEELER GAUGE SET OFFSET