Skirt
Flexible part of the mask in contact with the face.
Silicone
Silicone is an extremely flexible material. A silicone skirt adapts smoothly to the contours of the face, ensuring a watertight seal. It is a hypoallergenic material.
Micrometric buckles
The micrometric buckles combined with the notched strap on each side of the mask make for easy, precise mask adjustment, even when wearing gloves.
Internal volume
The volume of air trapped in the mask, between the face and the glass, represents the internal volume.
For freedivers and spearfishermen, the mask's internal volume should be as small as possible to facilitate compensation.
Compensation
Mask plating occurs on descent: as soon as the wearer is immersed, the pressure presses on the mask's flexible skirt, reducing its internal volume and pressing the mask against the face. To avoid this painful phenomenon for the eyes, it is important to compensate for the internal pressure of the mask and the external pressure exerted by the water. To do this, simply blow slightly through the nose.
Air is so precious in these sports that the compensating action must be minimal.