0.40 mm thick (=normal): Mask Rubber Anatomical with Hole for Eyes, Nose. One size will serve in (almost) all of the heads.

Once they are all moulded/shaped heads real, these hoods are amazing and comfortable to wear just on their own, or to be worn under a gas mask, for example.

Made of black latex 100% natural.

It is clear that they sought to be sure that the openings of the eyes are good, and especially, the holes of the nose are large enough and placed in the right place to allow the entry of sufficient air. So, you can get enough air.