3/8" unf x 1" Flange Head Bolt.
Just right for mounting your front caliper to the mounting bracket.
Designed with a larger flange than normal to ensure good clamping  to reduce caliper flex.
Also has a 9/16" hex, which is perfect when used with our other 9/16" hex head bolts, so you only need 1 size spanner when doing a quick front change!
plus it's drilled for lock wire