Last updated February 17, 2022.
The earliest example (as known to me) of Rowe Industries’ first attachable pickup for flat-top roundhole instruments appeared in their silver foldout Form D100, dated November 15, 1941, shown below. Just four items were included – the models FH and FHC for F-hole guitars and the RH and RHC for flat-top roundhole guitars. The suffix C in each case indicates the inclusion of a volume controller.
The two RH models comprise an upper flat brass plate with semi-circular ends and a lower U-shaped plate, both enclosing a shallow coil wound around a bar magnet. A steel spring, attached to the wide end of the pickup assembly, is inserted under the guitar’s soundboard. A movable metal tab is located at the opposite end of the pickup. This tab is designed to fold under the pickup during installation and swivel out under the soundboard when positioned in place. A rubber grommet ,which is located at the end of the tab, is designed to hold the pickup in place while minimising damage to the instrument.
This view of the pickup FHC is taken from the 1941 leaflet, Form D100.