The high-level anti-theft performance. The lock has been tested by sawing, cutting and hammering, but it is still stable. Each lock has 3 keys, and the key number is unique. Smaller size when not in use-the fixing bracket is made of reinforced plastic and can be folded and fixed on the Seatpost, the size is smaller when the bicycle lock is folded. After unfolding, the locking device can be extended to 0.85 m. After testing, it can lock three bicycle tires together, or lock the bicycle to a telephone pole or other safe place. The lock body material is built into the final zinc alloy, covered with reinforced plastics to improve safety.