This 31x50 is part of our special Golden Ratio series and is considered the most pleasing proportion to the human eye! Sausalito is our #12 heavy weight cotton duck canvas finished at 14 oz., sized and double 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. It has a robust paint-gripping surface texture and rugged body, 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. The 3.25" wide heavy-duty keyable cross braces allow the canvas frame to be tensioned in the middle, where the tension is needed the most...a unique design for which we earned a patent! Double tongue and groove frame corners provide maximum torsional rigidity. Cross braces are glued and fastened at the “cross” for maximum support and rigidity. Both corner keys and brace 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.