Check the listing for details. 10 Pack Duragrip Guitar Picks 1.5mm Extra Heavy Acetyl D'Addario 7DBK7-10. Color: Black, Condition: New. Listed at 9.74 USD. D'Addario Planet Waves Duragrip Guitar Picks Super Grip 1.5mm Extra Heavy 10 pack, 7BK7-10 D'Addario DuraGrip guitar picks feature a molded grip surface and provide superior traction while picking.Duralin (also known as Acetyl or Delrin) is a unique material with extraordinary combination of strength, stiffness, dimensional stability, toughness, fatigue resistance, abrasion resistance, and low friction. Normally used as a replacement for metal bushings and bearings in industrial applications, this extremely durable polymer is ideal for picks. Duralin picks are known for their bright "clicking" sound when hitting strings and are preferred by many soloists for their clear articulation on fast single note passages.