Apart from the steering lock provided by the manufacturers, you must provide additional anti-theft devices for enhanced security. These automobile security devices require additional time to break open, and hence, prove an effective deterrent even for a professional car thief. Devices such as steering lock , secret cut off switch, anti-theft alarms are easily available. There are many variations of anti theft alarms e.g. Vibration based , door based , ultra sonic based . A recent interesting variation is call back pager alarm , which is extremely useful if you have to park your vehicle out of sight. It is also advisable to change the Hooter of the alarm as all the Hooters' sound the same.