something like those neoprene ones, although bearing in mind that'll be less effective at taking out the sting. other alternative is to take the route of putting your optics on a riser to make up for the mask.
I have raised rings on my sniper rifle but I still cant see shit with the dye i4. So imma invest in a prescription ess and some flexible lower.
i'll settle for this then: https://www.amazon.co.uk/OneTigris-Tactical-Protective-Paintball-Adjustable-x/dp/B01KDWEB2C?th=1 as it is exactly what i'm looking for
I'd really suggest if you haven't bought already, please look at Heroshark on Facebook. You can get ones that just cover your mouth etc
other alternative is to take the route of putting your optics on a riser to make up for the mask.