One day I'll do a visual explanation on how Oscar's helmet and suit fit together, but for now I'll try and use my words to explain this:
Oscar's helmet is a glass-like bubble visor mounted onto a corrugated/collapsible neck which can be altered by the user manually to increase visibility slightly in most directions. The base is well insulated and has heat regulating elements set inside, the speaker and mic are also rigged into the base of his helmet. It has no internal lighting due to power management issues with the basic model suit.
To attach the helmet to the suit (as you may have noticed in previous pages with Oscar helmet-less there is no apparent mount or locking system for his helmet) you stretch the neck of the suit and pull it over the corrugation of the helmet. The suit and helmet base are layered/made with a material which creates a brilliant seal, the measurements are so precise it prevents the helmet from shifting - which is also aided by the corrugated base being moulded to the shape of Oscar's chest and shoulder.
But saying all of this, this doesn't prevent the risk that Oscar, being restricted by wearing gloves, has ensured the brilliant seal is true.