Stahlex U-lock This U-lock from Stahlex is in the highest security category (A) and has the ART-4 quality mark. U-locks without the ART quality mark also protect your bicycle sufficiently, but with most insurance companies you are obliged to use a lock with the ART quality mark. Specifications: Total length: 245 mm Shackle thickness: 18 mm Total width: 180 mm Weight: 2180 grams Shackle material: heavy hardened steel Security category: A Art quality mark: ART-4 Color: black Contents: 1 Stahlex U-lock 3 Keys