When the famous American banjoist William (Bill) D Bowen ran a teaching studio from 637 Broad Street, Newark, New Jersey, he sold the Bowen banjo which had a 12” hoop, 28 brackets and 20 frets, and sold for $50.
The instrument had a solid wood hoop inside of which were fitted 25 nickel plates brackets made of spring steel which were held in place by bolts through the conventional shoes. These brackets extended over the upper edge of the hoop to rest on a, 1/8dia ring fixed to the hoop. On top of this was a 5/16th dia. steel ring over which the vellum was stretched . Bowen claimed that “the steel brackets act as a spring by which you get vibration to each note”.
It is obvious he did not make the instruments himself which were possibly made by Rettburg & Lange