It should be recognised that a shackle that does not have any markings makes it difficult to establish its strength or compatibility with the safety chain. It is the responsibility of the vehicle owner/operator to satisfactorily address inquiries raised during any roadside audit by an enforcement officer.
Usually the diameter of the shackle pin is larger than the shackle body.
The strength of a shackle will vary according to its grade. An “S” grade shackle will be stronger than an “M” grade shackle of the same size.
Stainless steel shackles are generally unsuitable for trailer use due to the material’s general low resistance to bending stresses.
A Bow shackle will provide flexibility for greater angular movement compared to a “D” shackle.