This lock is an innovating black ring lock with keys. Thanks to the opening on the side of the lock, you can use the plug-in chain (41198072) as an extra lock to fasten your bicycle to a fixed object. The steel housing is corrosion-resistant and has an extra wide opening. Because of its wide opening, this lock is also suitable for mounting on bikes with extra wide balloon tyres or wide mudguards. The ring lock can be mounted using the accompanying fastening. The lock comes with two keys. Make sure that loose locks are stored away when bicycling to prevent damage and/or accidents. Tips: 1. The best way to secure your bicycle is with a permanent lock in combination with a cable- or chain lock, so that you can fasten your bicycle to an immovable object. 2. In order to enjoy using the lock longer, we recommend that you regularly spray the lock with silicone spray.