This is a Mabie Todd Swan Visofil 'V' Series V111 / 66 Ladies Emerald Pen c. 1936. The Mabie Todd model is V for Visofil, 111 for the small clipless ladies pen, and color code 66 for Emerald. Mabie Todd introduced the Visofil pen in 1935 to compete in the "ink visible" trend going on at the time. This is the longer 4 3/4 inch version of the V111 introduced in October, 1936. 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 Imitation Mother-O'-Pearl, Blue, and Emerald celluloid. It has a Number 1 size 14 karat gold nib, stamped SWAN over 1 over 14CT over MABIE TODD over & CO LTD.