In Thai magic, there are two types of 'body locks': the active and the passive.
The active body locking method applies to an aggressive person and wild animals, while the passive body locking applies to the body of the magician himself.
For example, if a magician is facing an insane and mentally sick person who is about to attack the magician, then this magician will chant 'om arahan' and blow a breath at the person to stop being attacked by the lunatic.
Similar active body locking method can be used to treat wild animals in the jungle too.
On the other hand, passive body locking method applies on the body of the magician himself for his own protection normally before this magician is about to take a long journey and that there are potential dangers along the road.
Old folks believe that whether a person is dead or alive, he should make all efforts to let his family members known. This is perhaps not a problem in modern times as the messages can be sent across very quickly.
In old time when a person must travel over hundreds of miles between two villages that were separated by maiden jungles, then a reliable method to make sure the person arrives at the destination 'dead or alive' is very important.
In traditional Thai magic, passive body locking ritual will ensure that a potential traveler reaches his final destination by whatever means. Even in today's situation, this passive body locking is still relevant and I myself am practising it consistently before I go into a jungle. Hence the effectiveness of body locking ritual should not be doubted.
The body locking ritual works on the belief that a person will not die if his soul and body remain intact. So, body locking is actually locking one's body and soul together with the help of the person's guardian spirit.
Once a passive body locking ritual is performed, the magician would be in a semi-trance state and the spell would remain so long as he does not consume water and food. In order to prevent the body locks from becoming void during a journey, foods should be taken in a specific way which differs from master to master.
In common practice, simple body lock ritual can be done by chanting a mid-length mantra accompanied with simple hand gestures. This common body lock ritual should be 'unlocked' once the magician arrived at a destination normally by invoking the help of 'lersi' or his lineage master or no one will notice his presence.
There is a more extensive uncommon body lock ritual that incorporates the immortality ritual. This is a more extensive ritual that requires a practitioner to spend one hour a day over a period of 9 months.
Personally, I like the simple one best however. If you are persistent, then you will find that Thai magic is a day to day magic and it is very practical.