Type I is steel chain intended for general service. Type I, class 1 is a special analysis alloy steel recommended for hazardous overhead lifting and wherever long life and extremely high tensile strengths are desired. Type I, class 2 is a special analysis steel which is heat treated as required to produce a chain having high tensile strength and resistance to impact loads.

Type II, class 2, mechanical communication chain is intended for use in pulleys having a 5/16-inch groove used on a line of signal transmission of mechanical telegraphs.

Shackles in accordance with this specification are intended for general use including rigging. Where stronger shackles are required for special use, refer to grade B high strength. It is general practice to use a shackle one or two sizes larger than the chain that is used with it. The proof loads shown herein indicate the maximum loads which the shackles may be expected to withstand without distortion.

End fittings in accordance with this specification are intended for use with fueling at sea rigging.