This system utilized a hinged hidden matchstick. Lift up a faux lever and the stick drops into position.
Houston pens from Sioux City Iowa are idiosyncratic in their full-length ring top form, with attached chains, and with unusual and elegant tapered barrels. Eye-dropper fillers date to the mid 1910s. Later pens included the Snap-Fil mechanism, covered by US patent 1,342,736 applied for March 23, 1918, and issued June 8, 1920. Pens can be labeled either Houston Snap Fil or General Manufacturing Co Snap Fil. The faux lever lifts only about 30-45 degrees, and a hidden hinged portion swings down perpendicular to the barrel. In actuality, the pen employs a matchstick filler with an integrated stick tucked under a faux lever. Unfold and push on this contraption to depress the internal J bar and sac, and with enough pressure, the smaller “matchstick” snaps back under the “lever” into its original stored position, allowing the sac to expand and fill.