Marlen is italian producer of fountain pens. It seems they offer also inks. I was given this ink during polish FPD (fountain pen day).
Marlen Brwon isn't very interesting. It can be described as an average brown. It's sold in generic 30 ml bottle. The color is medium saturated. The ink lacks lubrication but flows rather well. It's not waterproof.
Drops of ink on kitchen towel
Leuchtturm 1917, Kaweco Sport, B
Eversharp Skyline, Rhodia
FPR Guru, Lyreco Budger,