Strathmore Bristol Vellum pads are an economical, heavyweight paper in a choice of two surfaces. One side has a smoothly textured surface and is ideal for fine pen and ink, pencil and mechanical drawing. The other side has a medium textured surface and is ideal for a broad range of drawing and painting techniques including crayon, pencil, charcoal, and watercolour. Both surface textures are good for airbrushing. Strathmore 300 Series Bristol Vellum is acid free and has 20 sheets of 100lb paper available in 9" x 12", 11" x 14", 14" x 17" and 19" x 24" tape bound pads.