Pelikan M300 Black/Green Striated, M300 14K Fine, inked with Pelikan Edelstein Mandarin
The smallest model Pelikan, the M300 is purely a pocket pen and I can only use it for any length of time if I post the cap.
A great little writer this fine nib is marred by a discolouration of the nib. It doesn't affect the performance so I don't try to fix it.
I picked up this ink secondhand from a member of my local pen group who was disappointed in the lack shading. It does shade but not all that much other than that is a good citrus orange. On a side note I think this is an outlier in the Edelstein range as I believe unlike all the others it is not named for a precious stone but for the citrus fruit.