The hole on that page.There are adjustments to the appropriate sound. Must have the well design and calculation? And a black thin wadding inside that prevents dirt and water into the speaker.
Hole on the tuning function properly. Must be designed and calculated well in the field and also fiber thin black inside. The act prevents dirt and water into the speaker's floor.
The pores on the face.A tune for proper. There must be designed and calculated.And the inside is also black thin fiber sheet inside. At the dirt and water into the speaker again.