Marine Green WASP VACUUM-FIL standard size

 In 1934 Sheaffer introduced their version of the vacuum filler in a sub-brand they called VACUUM-FIL. This sub-brand was renamed the WASP Pen Co in 1936. They used a sub-brand for the initial release of the vacuum filler as a means to work the design and manufacturing process. This filler is a large departure from the lever filler that Walter Sheaffer patented in 1908. The first Sheaffer Balance with a vacuum filler appeared in the 1935 catalog. The only notable design change was the replacement of the blind cap and two piece filler knob with an integrated celluloid filler knob. This pen is probably from 1936 after VACUUM-FIL became WASP since both brands are on the barrel imprint.  The barrel has darkened from its original pale green but it remains transparent enough to see the ink level. Otherwise the celluloid is in excellent condition without marks, cracks or damage. The cap clip has worn plating. I've replaced the filler rod with one I've custom made from black oxide coated stain