The smoother surfaces of Crescent Hot Pressed Boards are designed primarily for marker, pen and ink techniques that may require sharper detail. Their non-porous smoothness allows pens to flow clean, sharp and uninterrupted across the board. They also work well as airbrush boards.All Crescent Hot Pressed Boards have gray cores.No. 20 has a cool white tone and smooth, high rag content surface and is medium weight.No. 201 has a warm white and smooth, high rag content surface and is medium weight.No. 205 Has a smooth, high rag content surface. It's bright white and is heavy weight.No. 215 has a smooth, high rag content surface. It's bright white and is medium weight. Sold as [PACK OF 15].