With a TOTAL CROSS SECTIONAL AREA of 400cm or more, this piano is built to stand the test of time. The CSA is calculated by multiplying the width and depth of each post by the number of posts and it serves as a measure of the structural integrity of the piano. Like the curved rim of a grand, the back-frame of an upright is responsible for overall structural integrity and maintaining the soundboard crown throughout the years. The stronger the back-frame, the longer a piano will last and the better it will perform later in life.