This 16x16 is of equal proportion. Sierra is our #12 heavy weight cotton duck canvas finished at 14.6 oz., sized and triple primed with archival quality acrylic gesso, producing a ground impervious to paints leaching through and harming the fabric. Suitable for most all paint types, like oils, acrylics, and alkyds. With it's heavier weight, it tends to be stronger and slightly more uniform than other heavy weight canvases in it's class. And it's ideal for heavy paint or impasto. There is a 1/2" gap between the canvas and frame, eliminating the unwanted lines that occur when the gap is less. We never use finger joints in our wood frames, which often fail under tension and over time - the glue joints give-up, and are unsuitable for paintings intended to last for centuries. No brace required for this size. Corner keys are pre-installed. Stretched using our proprietary MuseumWrap method, producing a drum-tight-stretch up to 50% tighter than other methods, and with balanced tension across the surface. The corners are uncut and neatly folded, making it possible to remove and re-stretch the canvas on the same size frame.