Fed Mikron Preseries camera has the rounded corners and a fixed door wrapped around the bottom. "Mikron" is engraved in script letters on the front with FED on the top.
My early Fed Mikron #6800566 has the red commemorative engravings "25 years of Kharkov city liberation" on it's rear.
# 6800403 A.Nikitin
# 6800566 SovietCams