This speaker contains PM4 technology:

The new PM4 diaphragm incorporates a new high-tech polymer never used in the audio field before.

It offers a stronger union between the dome and the coil support, and therefore better behavior in handling high power and long periods of work.

At the subjective level, which is also a relevant part of the development process at Beyma, in our opinion it offers a more natural sound when compared to other polyesters.