Ultra-hardened steel U-lock with large, 18mm hardened steel shackle and all-metal lock mechanism. Fully housed body and rotating lock cover for corrosion resistance. Sold Secure Gold Standard. Includes 2 keys and frame bracket. Ultra-hardened steel U-lock with large, 18mm hardened steel shackle and all-metal lock mechanism. Fully housed body and rotating lock cover for corrosion resistance. Sold Secure Gold Standard. Includes 2 keys and frame bracket.