This heavyweight, acid-free sketch paper is ideal for experimentation or perfecting techniques. Spiral bound with micro-perforated sheets. Contains 30% post-consumer fiber. 60 lb / 70 sheets. The Strathmore Windpower line of artist papers have been manufactured with emissions-free, wind generated electricity. The manufacturing of this eco-friendly artist paper is certified through the Green-e Marketplace Program, administered by the non-profit Center for Resource Solutions. Strathmore pioneered the practice of using recycled pulp to make high quality fine art pads and they continue that tradition by offering 30% post-consumer waste in the Windpower Drawing and Sketch products. Strathmore’s commitment is to give artists the greener choices they want, with all the Strathmore quality they have come to expect.