A good chain lock has a solid construction, but still offers a high degree of flexibility with simple operation and can be used practically anywhere and on any fastening object. The thicker the chain link, the greater the security, especially if the chain links are made of hardened steel. The locks generally offer good value for money and, regardless of their length, can always be conveniently wrapped around the seat post and carried, even if a solid chain lock weighs quite a bit.
Although chain locks are not quite as robust as the best folding and U-locks, they are very resistant to external influences due to their sometimes solid construction.