The power of 300 lb. Arches paper meets the portability of a watercolor block. Superior quality, 100% cotton rag, natural gelatin sized, mold-made paper. Made in the Arjomari Mills of France since 1492. The paper is bound on all four sides for rigidity and to prevent warping. The cold-pressed sheets are 100% cotton, acid-free and buffered with an anti-microbial agent to help resist mildew.