The Alarm Chain 10 combines a 10mm square link chain with a loud 90dB alarm. This multi-purpose alarm chain lock will keep your bike and other valuable items secure from attack and the alarm will scare off any would-be thief.10mm square link chain.Loud 90dB alarm siren.Robust hardened steel construction.Protective chain cover.Batteries included (2 x CR2032 batteries).3 keys included.Replacement key service.2 year warranty.The Alarm Chain 10 has a key replacement service so that if you are unfortunate enough to lose all your keys a new one can be made up. Just remember to take note of your key number and keep this in a safe place.