The Oxford Alarm-D Disc Lock is a high security disc lock with an integral 120dB alarm system.Loud 120dB alarm siren16mm shackle3 x high security keysLong-life Lithium CR2 batteryThe Oxford Alarm-D Disc Lock boasts a staggering 16mm shackle and a high tech pick-resistant locking system to ensure that it is almost impossible for anyone to get through it. Even if someone does manage it, this lock has a 120dB alarm system which can be easily heard from a distance. This disc lock has a replacement key service. When you buy the disc lock you simply note down the number which comes attached to the keys on a metal tag. Then keep this in a safe place and then in an event that you are unfortunate enough to lose your keys it will be possible to get a new one made up.