This category includes all the guitars with what is called a double-top which is to say a top made of two thin layer of wood glued togetherwith some nomex or balsa. the Nomex or the Balsa strenghten the tops which do not need any bracing. The bracing is just there to tune the top. The back and sides are usually made with massive wood. These guitars are light and very responsive, with a huge projection and often a dark sound. The tricky points for the luthier are the balance between the projection and the sustain/ovetones and the string separation which can be difficult to get when the projection is too strong compared to the sustain.