This photo shows the bottom side of a soundboard. Wooden structures are glued to the 1/8" thick soundboard to both strengthen it and divide it into tonal areas which has a great effect on the quality of the sound produced. The wooden piece on the right is the 4' hitchpin rail. The 4' hitchpins must be secured in the middle of the soundboard, but the soundboard is too thin and weak to resist the tension the strings placed on these pins. As a result, a thick hitchpin rail is glued to the underside of the soundboard to accept these pins and hold them securely. The three pieces on the left are the ribs, which serve, among other things, to keep that area of the soundboard flat. To the right of the ribs is the cut-off bar that, along with the bridge, divides the soundboard into distinct areas for proper tonal development. The hole between the first two ribs is where the rose will be installed.