I have a rOtring I've had since university or even before. It's from before 1989, but I have no clue what model it is. (my dating it might be flawed since I'm not getting any younger ;-) )
the body is made of messing and blackened (but some has worn off)
the thread of the pen part that screws into the body is in inox or nickel
the nib has rOtring on the side and M on the other side
have always been very fond of it
Does anyone an idea as to what model?