A butch, square-edged plectrum, inspired by a Galalith plectrum, spotted in a 1936 Gibson catalogue.
This shape, regardless of the material, is loud, surprisingly loud. The big squared-off grip part allows for a maximum of energy to flow into the relatively slender tip, and pass that energy on into the string. Very efficient.
Interestingly, in the 1936 Gibson catalogue, this shape is paired explicitly with the material ‘Genuine Gallolith’ (sic), in an ‘extra heavy DeLuxe weight’, presumably to balance the loudness of the shape with the slightly mellower, warmer tone of the Galalith.
But make no mistake, this shape works very well with modern resin, as well… good tone, and loud…