This is a Mabie Todd Swan Visofil 'V' Series V211 / 60 Black c. 1935-1936. The Mabie Todd model is V for Visofil, 211 for the clip pen, and color code 60 for Black. Mabie Todd introduced the Visofil pen in 1935 to compete in the "ink visible" trend going on at the time. This is the longest version at 5 inches introduced in September, 1935. The Visofil V Series is a uniquely designed ink sac pen with a clear plunger providing a view to the ink level. The sac actually is cut at both ends, with one attaching to the section and the other attaching to the spring loaded plunger. Repeatedly pressing the plunger draws ink into the sac and eventually the ink level can be seen through the clear plunger. The cap top is black ebonite stamped with the Mabie Todd Swan logo highlighted in white. This pen came in Italian Marble, Black, Russet & Jade, Brown Amber, and Amethyst & Gold celluloid and has a 1/4 inch wide rolled gold filigree cap band. It has a Number 2 size 14 karat gold nib, stamped SWAN over 2 over 14CT over MABIE TODD over & CO LTD.