I don’t know LOL. It’s just the regular heat Source scope. The fog changes throughout the match in Vondel. It will clear up as the match progresses. Also, the view through the scope can be affected by your surroundings. If there is a ledge or wall just in front of you it can give the Heat source a glare. You have to hang the rifle over/past the ledge and the glare is improved. It puts you in a more vulnerable position being more exposed, but you can see your target much clearer. Thanks for watching!