1934-7 Marine Green VACUUM-FIL fountain pen

In 1934 Sheaffer introduced their Vacuum-Fil filling system under the sub-brand VACUUM-FIL. The filler did not come to Sheaffer Balance pens until 1935. I've often wondered if the objective was to work out the kinks of production and also gauge interest prior to risking the company reputation. Later, Sheaffer renamed the VACUUM-FIL company to WASP for Walter A. Sheaffer Pen company.Sheaffer Balance pens were available in marine green celluloid from 1930 to 1935. However, they were only lever fillers. Marine green vacuum-filling pens were available only from VACUUM-FIL.I love these pens and also vacuum-filler from WASP. I keep almost every VACUUM-FIL and WASP pen I find. I would keep this pen, too, if I didn't already have one exactly like it. It is gorgeous.The transparent celluloid has darkened a bit. Yet its transparency remains clear enough to easily see the inner workings and the ink level. The plating on the trim is in very good condition.The nib is not hallmarked (e.g. 14 kt) but