Quick carpet photo in bad lighting.
Out of the box was equipped with a slant brake and came with one of the "Gen3" polymer mags Zastava USA is selling. Also in the box was a 3-piece cleaning rod and the 1913 rails Hogue uses with the handguard.
Swapped the slant brake for a Manticore Eclipse. Have a UTG M70 scope rail with a cheapo red dot on it as well.
I had my M90NP setup identical to this, just in green, many years ago. It's probably the most practical/cost-effective modern setup for the M90. I may try swapping it with the M90NP's current config (US wood and Bonesteel folder) but I may leave it as-is, not sure. The wood and steel is a heavier option than the all-polymer.
As to mag fitment, the Zastava polymer fits and locks, just kinda tight. It wears in fairly reasonably though. AC Unity 5.56 mags were about the same. The metal M85 mag is smooooooth as butter though. Definitely the best option, though you give up the BHO with it. Tried with Bulgarian Circle-10 waffles as well; the smoke ones half-locked, solid black wouldn't lock. Don't want to modify mine but a moment or two with a file on the rear lug would probably fix it. Everything tested fine feeding with Magpul dummy rounds.
The trigger is really nice. Little bit of a long take up, but there's a nice wall and clean break. I have a Century RAK-1 in the M90NP, which is "not bad" for an AK trigger, but this is light years ahead. And both of those are better than the old Tapco G2.
Action feels nice, ejected the dummies with some authority cycling by hand. All told, I'm pretty happy with it.