Stillman & Birn Zeta Hardbound Sketchbook 5.5x8.5 inch Stillman & Birn from $19.96 $24.95 Qty. Add to Cart SKU: SB900580 This item is currently on backorder but you can still purchase it now and we'll ship as soon as more become available. Stillman & Birn Zeta Hardbound Sketchbook 5.5" x 8.5". Stillman & Birn ZETA Series Sketchbooks feature 80 lb. (270 gsm), Natural White, Smooth surface paper. Excellent for multi-media artwork. Tweet