Home » Products » MISC./SPARE PARTS » Tone-Lock™ Bridge Lock Nuts Replacement lock nuts for Faber® Tone-Lock™ bridge. Not for use with any bridge except Faber® Tone-Lock Bridge. Tone-Lock™ Bridge Lock Nuts for ABR-1 bridge posts (6-32) (4) Tone-Lock™ Bridge Lock Nuts for 4mm bridge posts (imports and Faber® 4mm conversion posts) (4)