This Arches Watercolor Block contains 20 sheets of 140 lb. (300 gsm) cold press, acid free, 100% cotton watercolor paper. Arches has a tradition of creating high-quality papers for over five centuries. This watercolor paper is superior quality, mold-made paper from the Arjomari Mills of France. This convenient block is glued on all four sides, keeping your surface taut and allowing you paint right on the block.