The oxford alarm d u lock mini is a great lock to own if you are out and about on your bike multiple days a week and using outside bike storage the alarm d mini lock is constructed from high quality materials to provide an extremely high level of protection the weatherproof alarm is powered by a long life lithium battery and has an output of 120 db which is at a similar level to the siren on a fire engine or a chain saw you have the option to activate the alarm when you are locking your bike