Stillman & Birn Archival Quality Sketchbooks - Epsilon Series Hardbound - This line of archival quality sketchbooks has a simple premise: When it comes to sketchbooks, paper matters! All of the books in this line are beautifully bound in the United States. The covers are extremely solid and the books literally feel different in your hands than sketchbooks made by other companies- these have a weight and sturdiness that you will notice right away. Made entirely out of archival materials, you will love these books. The Epsilon Series hardbound sketchbooks are suitable for line drawings without feathering or bleeding. The paper is 100lb. (150gsm) natural white and has a plate (hot pressed) surface. There are 62 sheets of paper per sketchbook.