Why do I hear a sound coming from the frame arms when I shake the DJI Matrice 3D series?

A sound can be heard coming from the frame arms of the DJI Matrice 3D series when shaken due to the particle dampers installed in the LED covers at the end of the frame arms to dampen frame arm vibration, ensuring reliable, long-time flight in various environments.

It is normal for the particle dampers to make a sound when shaken.