The 1920's- (?) early 1930's saw a few brands of BIg Black Pens with Big Transparent Barrels.
Postal was one. Dunn (as in the Dunn Camel) another. Often forgotten is Sager with its Transparo.
At the Ohio Pen Show, Nov 2010, a fellow was strolling down an aisle carrying a crate of pen trays. I literally called out to him (hey, nothing ventured nothing gained) to ask if he was looking to sell pens. You can guess where this leads.
Rummaging through about 200 pens, I managed to grab about 20 for my collection and for the website. One was an oversized Sager Transparo, one I've wanted to grab for no small time, as I've photo'd Dunns and Postals, but not a Transparo.
So... here she be...
regards
David