Artist Paper made from 100% long fibered cotton rag, resulting in exceptional strength and durability. They are tub sized (surface sized) with Gelatine. For watercolor and all painting and drawing media(not oil), print press, block print, invitations etc. There are envelopes that they are made for these to fit into (C6 & C5). They can either be slipped into the envelope or folded as a card and put into the envelope. A great DIY for wedding or party invitations. Acid free.