Helmet Bands w/string/strands

[Landserstudent]

Especially in photos of Ostfront action, German soldiers are shown wearing helmet bands with strings/strands that hang down over the face,neck, etc.
I think I read some place these were used to keep the insects off the face and neck, but could also be used as masks, as the strands are quite thick all around the helmet band.

What is the name of this piece of equipment? How easy are they for collectors to find? (With all the digging in W. Russia, Estonia, Latvia, etc., maybe some are showing up?).

-Landserstudent