Funnily enough I've been searching the archives on here for these stocks for the last week, couldn't remember the name.

As above there was a bit of fanfare in 2019 when ZRS were meant to be partnering with Cometa, and IIRC before that when the owner was promising drop in stocks for some models, but nothing seemed to come of it. Maybe Norica had a better offer? Incidentally I can't find ZRS' website anymore.
Either way the whole ZRS thing has been going on for a while now, I'll get excited when they actually release a gun.
And even more excited when they release a gun that doesn't look like an SMK syntarg with utterly pointless open sights dropped into a weird looking stock.