Ray-JrMALL MR.Jiang Bicycle Bike 110dB Motion Sensor Anti Theft Security Alarm Annunciator Lock Traditional chains, padlocks and U Locks only do half a job and can be pretty easily removed by those who know how, but even the sight of this alarm will have even the most determined of thieves thinking twice.If your bike is moved, the alarm will spring into action and give off an ear shattering shriek. No thief will want to hang around when this alarm goes off.Its 3 sensitivity levels allow you to determine how much movement is needed to trigger the alarm.When triggered alarm had already sounded for 5 times, If triggered again within 5 seconds , it will sound continuously for 15 seconds. Product size:10 x 6.5 x 4 cm. Color:Black. Fixed ring diameter:2.7 cm.