We only use carefully selected, naturally seasoned wood. The outer area of the top, where the top is attached to the rim, is sanded thinner than the center. All of the parts are secured tightly using a specially formulated glue, which produces a result close to the hide glue. Grand Auditorium, Classical Auditorium and Semi-Jumbo all have a smaller size body, but we increased the depth of the body to obtain a big sound. For the back we offer “Flat Back”which has a light arch from the bass side to treble side. “Round Back”has dish-like shape, arched on both the bass side and treble side from the heel to the bottom. Both models have a wonderful tone and sustain, but “Round Back” will emphasize more overtones and give a powerful bass, increased volume and sustain. All of the models have either Venetian Cutaway or Florentine Cutaway.