Wirt pens with special cases Overlays, spiral cases, faceted cases. Overlays Overlay pens were precious. They will almost always be engraved. Similar pens, one very early two-piece overfeed, and one post 1903 underfeed. Cable Twist Faceted pens The underfeed hexagon pen has an imprint for a patent I can’t identify. The smaller pen with the round cap has 10 sides and a typical single line imprint. The oversized pen has a typical two line imprint. Faceted pens appear to have been made for at least 20 years.. Mottled taper caps Mottled hard rubber taper caps are much less common than black ones. Unusual case with large center This odd pen was found in the catalogs, shown here. The top pen has a three line imprint on the cap and underfeed to match. The spiral case has an overfeed. They are dropper fillers.