Johan Perremans

The MiG-21MF is essentially the export version of the SM. SM's were built in Gorkiy and most - but not all - MF's were built in Moscow. The main differences are in radar and avionics and are invisible from the outside. This means Eduard's kit can be built as an SM. Matter of fact, the plastic as is simply is an SM; you will need to scribe a panel line in the upper wing halves to make it into a Moscow FM. Eduard provides a template for scribing but forgot to mention this should only be done for Moscow built MF's.
Now, hang on, because it gets confusing: a few 100 MF's were built on Gorkiy production lines in the early 1970's. Since the factory had switched to building the BIS, a number of BIS features were integrated in these late MF's: a new cockpit lay-out and some hull details. These fighters were exported only to CSSR, DDR and Bulgaria. CSSR late MF airframes In Czech service were later equiped with NATO avionics and are known as MFN.

Now, what can be built from this box?
SM: don't scribe panel lines, build OOB
Early (Moscow) MF: do scribe panel lines, build OOB
Late (Gorkiy) MF: Eduard does not mention this option but it does include a suitable cockpit instrument panel. Don't scribe panel lines, use appropriate PE part No and check references to make slight alterations to hul panels. You will need to do some filling and scribing.
MFN: same as late MF, but you will need aftermarket PE for the NATO modified cockpit instruments.

Actually the kit will also allow you to build earlier S and M versions. For S, do as SM, for M do as MF since all differences are internal.