This is a St. Regis branded bulb filling fountain pen made in grey etched celluloid from the late 1930s. The clip is stamped PATD at the top and is identical to EPENCO stamped clips used on certain 1930s EPENCO pens. Those clips are based on the 1920 Eagle Pencil Company clip patent. The pen is a bulb filler with a long breather tube extending from the back of the feed into the transluscent ink chamber barrel. The pen is operated by removing the end cap and squeezing the bulb. The end cap screws onto a metal bushing that also serves as a trim ring when the end cap is on. This design follows the description given in the November 3, 1936 Eagle Pencil Company patent and is used on similar gold plated stainless steel nib EPENCO bulb fillers that sold for $1.95 per dozen to dealers. Those clues point to this pen being made by The Eagle Pencil Company in the late 1930s. The celluoid is very similar to the "Etched" celluloids used by Conklin on their All American pens in 1936. The 14 karat gold nib is a replacement, moved from a broken Wearever. The pen is 5 1/8 inches long and the trim is lightly gold plated. The cap band is a wide band with painted rings to make it appear as a triple band cap.