Does anyone know if it’s absolutely necessary to have the rubber gasket on the back of the Norotos one hole shroud? I picked up one of these shrouds recently, but the rubber on the back was missing. This is the shroud I have: 
Supposedly the gasket helps seal the shroud to the helmet, but if I tighten the screw down properly will that be GTG, or do I need the rubber gasket?
When we switched from Krylon’d helmets back to helmet covers, I’m 99% sure I didn’t use the gasket on my Norotos. I’m not sure how it would be on a slick helmet, since the nylon cover kind of acts like a gasket. But if I recall correctly (and I’m pretty positive that I do) that I didn’t use the gasket, it shouldn’t be a problem.
Thanks for the response. I’m thinking it should be okay too. I’m not running a helmet cover on the MICH, but the shroud seems to be on there pretty solid with no movement/rotation at all.
I’m curious as to why the 3-hole version doesn’t require or come with the rubber gasket, but the 1-hole shroud does…
I think it’s an anti-rotation / slippage thing more than anything. The shroud is more prone to rotation when there’s only one point of attachment in the center…opposed to 3 points where it can’t turn on itself. Never had an issue with it though.
It is there to help with anti-rotation. It is not necessary, but there are no other ways to keep it straight.
You could probably get any similar shaped o’ring or other suitable synthetic tension shim, a hardware store. I would, at the least, put loctite on your screws.
Vibration on trucks, helos, boats has loosened my NOD (and other) mounts before.