Not to be disagreeable, but I believe the bottom is a chinese hider....Ive never seen a PM90 that had bluing that nice, that looks more like a polished chinese bluing rather than the more matte dull finish I typically see on romanian stuff. Ive got an OG romanian MD90 device and its considerably rougher than that. To me, it looks more like the 84s hider, perhaps an aftermarket import brought in for the US market. The top one is definitely a polytech hider. Ill look through my old Kengs catalog tonite and see if I can find any more out for you.