Yellow colored shackle to further remind rider that disc is locked. Large 55mm x 55mm (2.17" x 2.17") opening fits many disc and rotor openings. Massive 16.8mm (0.66") hardened steel shackle resists all attack from cutting, prying or jacking. X4P Quattro Bolt locking system secures the shackle on four sides for ultimate protection. Included disc reminder helps prevent accidental drive-offs.