Stillman & Birn Zeta Hardbound Sketchbook, Heavyweight 180lb, Natural White, 25 Sheets, 5.5x8.5 Contain 25 sheets of extra heavy-weight 180lb archival paper The paper is natural white in shade and has a smooth surface Smooth surface ideal for pen and ink-colored pencils-water based markers ph neutral as well as lignin and chlorine free covers made of extra heavy weight binders board