Now the best of two worlds are bound together in one sketch book. These spiral-bound books contain two of the most popular Strathmore papers: 400 Series watercolor and 400 Series sketch. They are great for on location studies. Each book contains 15 sheets of 140 lb. cold press watercolor interleaved with 15 sheets of 60 lb. sketch paper. Use the sketch paper for preliminary drawings and notes to prepare for the watercolor paintings.