Going strictly on the nib, we're going to call this the Boston Safety Pen. There is no company branding on the cap or barrel. Yet, each has an matching imprint of a patent date of July 5, 1904. It looks like a later 1920s ring-top, but there is no lever. This appears to be a traditional eyedropper and not what we think of when we think of a safety pen. An additional imprint says "18 1/8." We think that means it is 18k gold filled at 1/8th thickness. There only appears to be brassing at the very edges. The ring top's top plate spins when the tassie is turned. You will write a nice fine to 1mm line with this semi-flex nib. The nib is a little stiff but flexes with gentle pressure. Click the headline for close-ups. 9.3cm capped.