The On Guard bulldog U-locks are constructed of 13-Millimeter hardened ultra steel shackle with reinforced sleeve over crossbar and cylinder for added security. Available in key or combo lock; keyed locks include 5 laser cut keys (1 lighted) and all tube quick-release mounting bracket. 4.6 Tons pull strength with anti-drill and pick resistance. 13-Millimeter hardened ultra steel shackle with reinforced sleeve over crossbar and cylinder for added security. Bulldog includes free 1-year 1251 dollars anti-theft guarantee.