Stylomine was a succcessful and prolific French manufacturer of good quality pens and pencils. They invented the “accordion” bulb filler in the 1930s, an accordion sac over a glass breathing tube with a glass ampule to hold the ink; in addition, although Parker got the credit for the first hooded nib, Stylomine’s preceded theirs to market. Their 303 series was their biggest seller from the 1930s-1950s, in various styles and sizes.
This 303 is a postwar pen, in black plastic (possibly Bakelite), with the accordion bulb filler and plastic ampule and breathing tube. It’s a slimmer pen, .9cm at the case of the cap, but at 12.5cm long capped, standard length for a French pen. The pen fills easily, and writes a smooth fine. It shows some wear, but is a nice writer.