Revenant

Mono-Scopic S-Scanned Retinal Image Projection Half Face Goggle
 

In essence, this helmet is a simpler version of the 9 series.  The difference is that this helmet has a simplified air filtration system and is not appropriate in chemically and/or biologically polluted areas.
 

Notes: The Half Helmet.  My personal favorite.... But I'm sure you're sick of hearing that.  Allowing for both the Nightmare's sight of bio-etheric energy and the vision of one eye, seems practical don't it?  But then, I think there'd be a problem with depth perception.