The Vernon McAlister guitar is a metal-bodied Duolian made around 1931 to 1933 by the National Stringed Instrument Company. The Duolian was the least expensive of the compnay’s line. The guitar sold for about $32.50 and many thousands were produced.
The Duolian is a single resonator guitar. A somewhat conical metal plate vibrates to amplify the sound of the strings and the body sort of acts as a speaker cabinet. (National also made a three-resonator guitar that was somewhat more expensive.)
Because of its low cost, more than $20 less than a Martin D-18, its sturdiness and its loud, resonator-amplified sound, the Duolian was popular with performers on a budget. The guitar was loud enough to not get drowned out by other instruments in a band.
National resonator guitars were originally marketed to jazz and Hawaiian musicians. Most models were available with either a round or “Spanish” neck or a flat or “Hawaiian” neck to make it easier to play with a slide. The Vernon guitar has a round neck.
Over the years the stout, loud, inexpensive National guitars were adopted by many blues performers and it is in this context that they are best known today. However, National guitars and especially the Duolian, were widely marketed and wound up in the hands of many people during the Depression years and thereafter.