This Link Fixing Bolt can only be used with Shimano BR-CX70 cantilever brakes.
If the correct Link Fixing Bolt is unavailable you can also use the fixing bolt from the following brakes:
Shimano BR-CX50
Shimano Deore XT BR-M770
Shimano BR-M421
These are a "B" match which indicates that the parts are usable, but differ in materials, appearance, finish & size etc.
Genuine Shimano replacement part.