This 20x20 is of equal proportion. Medium weight Belgian Linen finished to a primed weight of 13 oz.. It's double sized and single primed with archival quality oil primer, making the ground impervious to paints leaching through and harming the fabric. For oil or alkyd paints only. It is highly absorbent and has excellent qualities of luminosity. It has a warm yellowish hue and is very popular among oil painters. It's an extraordinary painting surface! Linen is very strong and has natural oils within it's fibers which keep it flexible and help prevent disintegration over time. The surface has a smooth tooth, although not considered of a portrait texture. 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. 3D Pro features double tongue and groove corners, a feature for which we earned a patent! Each corner features 4 pre-installed keys. 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.