What kind of 4 pot calipers? Metro or something more exotic?
Believe the metro ones used 3/8" UNF thread as well as the Mini ones, not sure why you think they should be metric :?
Any flexible hoses for minis, or 4 pot conversion hoses for metro to mini should, I believe, be UNF. No doubt if I'm wrong, Jerry will correct me :wink:
Dave