This specification covers positive locking self-retaining bolts. Classification. Bolts will be of the following types and classes@ as specified (see 6.2): Types: Type I Head end actuated. Type II Thread end actuated (solid shank). Classes: Class 1 CRES bolts@ magnetic (PH13-8Mo). Class 2 CRES bolts@ nonmagnetic (A286). Class 3 Titanium bolts (6Al-4V). Class 4 Nickel Alloy (718).