Sturdy lock cylinder - The locking head is made from heat‑resistant ABS environmental protection material. The zinc alloy cylinder uses an international standard lock pin system, and the unit is dustproof, waterproof, drill‑ and sawing‑resistant. Hardened steel chain - Robust high‑performance chain with anti‑drill and anti‑saw protection. Durable and reliable. Total length is 90 cm. The chain can be linked with other chains for extended security. Easy to use and portable - Smooth, precise dial movement. Clear, large digits that are easy to read in low light. No keys required; the combination can be used quickly and conveniently. When not in use, wrap around the bike frame or handlebars for compact storage. Keyless convenience - Advanced 5‑digit combination with over 100000 possible codes reduces the risk of losing keys and provides dependable access control. Use scenarios - Urban commuting: secure a bicycle to a rack or post at shops, workplaces, or campuses during short stops. - Transit and travel: lock to fixed structures at train stations, bus stops, or outdoor areas while you are away. - Flexible security: extend or combine with other chains for longer reach when needed.