This is a mandriola, a mandolin with 4 courses of 3 strings, built in maple, rosewood and spruce. The strings in each course can be tuned the same, or as in this case, the top two as normal, and the third an octave below the others, for a fuller rounder sound. The scale length is 350mm and it is strung with Pyramid ’low octave’ silver mandriola strings.