I scored one on the cheap a year ago, new.
It was going on an SR-15 so it seemed smart at the time. But I don’t see much utility in having a spare battery on a T2 unless I was being dropped off in a hostile jungle for 3 years.
I’ve seen dudes struggle with them in carbine courses because they came loose and killed power to the optic. They have to be screwed on pretty dang tight.
Just hit the stock notification with all the common vendors such as Operation Parts, et al.