Witness Chamber Pendulums
The concept of the Witness Chamber Pendulums was developed by Father Abbe Mermet, a priest from Switzerland, who first placed herbs inside the pendulum (after drilling a hole inside it), and proved that the vibration from the piece of matter placed inside the pendulum emits its vibration around it.
This vibration can also be sent to people. His outstanding body of work, written in French, is the framework of today's European School of Dowsing.
With proper care and use, a pendulum will last a lifetime.
The only part that may require replacement due to wear and tear would be the sting or chain that the pendulum is suspended from.
To read more how to replace string or chain...