These are Castle Arts sketchpads, featuring four different paper types, including black, white, beige, and Bristol.Each pad contains 20 sheets of A5-sized paper (210 x 148mm).The papers range in weight, from 118 gsm for the beige portrait paper to 250 gsm for the Bristol board.The black paper sketchpad is highlighted for high contrast drawing, while the others cater to different drawing media.