An extraordinary combination of strength, stiffness, dimensional stability, fatigue resistance and low friction.The DuraGrip guitar picks are made from D’Addario Duralin (also known as Acetyl or Delrin) is a unique material with an extraordinary combination of strength, stiffness, dimensional stability, fatigue resistance and low friction. Unlike other standard delrin picks, DuraGrip features a unique, stamped checkerboard surface that gives superior grip while playing.