16.8mm massive ultra-hardened steel shackle provides maximum cut resistance Unique OnGuard cylinder offers optimum resistance against physical attach and picking Reinforced sleeve over crossbar and cylinder for additional security Triple layer steel crossbar Quattro bolt locking mechanism with dual lockdown protection provides unequaled strength by locking the crossbar to the shackle on 4 sides, maximizing pull resistance Rotating dust cover protects cylinder Protective vinyl coating on shackle Double rubber coating on crossbar Anti-theft protection plan STD 16.8mm 4.4 x 8