Bowhntr6pt
Master
Then there are the enclosed emitter types (link below), which supposedly have the advantage where dirt and moisture are concerned, but I'm not so convinced. The glass can still fog on the outside (and hopefully not on the inside!), and can still get dirty, and the solution would be the same as with an open emitter: wiping off or blowing out, or maybe in an emergency just popping off a round to throw the dirt or moisture off : )
I've never hunted hogs, so I don't know how you guys do it, but I could picture someone laying prone in tall grass waiting for the hogs to come over, then trying to take the shot only to have a brown recluse blocking the emitter : )
https://www.steiner-optics.com/battle-sights/mps
Funny you mention this...