ONGUARD 5010C Bulldog Combo Standard Bicycle U-Lock 13mm hardened steel shackle X2 double bolt locking mechanism Heat treated steel crossbar with hardened tube, coated with rubber Double locking mechanism for extensive holding power Set your own 4 digit combination(10,000 variations) so no keys to lose or forget Includes All Tube mounting bracket Anti-theft Protection offer Rotating dust cover Protective coatings on the cross bar and shackle