"Mak90" is the name of the Chinese AK as made by Norinco in the early 1990's. I have one and they are, with the exception of the finish, excellent.
The double hook, as opposed to the single hook, trigger makes for a relatively smooth pull.
The firing pin is spring loaded, unlike most AKs, so a slam fire is nearly impossible.
The gas tube seems to rattle a bit as typical of Mak90's.
Bolt and carrier are hard chromed for ease of maintenance.
Dust cover is not ribbed.
The angle cut on the rear of the receiver was to attach it's factory bunghole stock. Installing the standard AK stock, assuming you've added the appropriate number of US parts, leaves a somewhat ugly void.
I like mine well enough that when it came time to cull the herd, the Romanian AKs went and the Norinco stayed. Heh, heh, I've probably bagged 100 desert hares with this thing.