Designed so that the canvas is always 1/2 inch away from the edge of the bar, the BEST Medium-Duty Stretcher Bar - 32" stops ghost impressions from forming on the canvas itself. The back edge is rounded so that the friction on the canvas is significantly reduced. This makes for a tighter and more even painting surface which, in turn, makes for a smoother canvas. Cross brace installation is made quick and easy with the slotted backs of the bars. For durability, this stretcher bar is made of white pine wood that is dried in a kiln.