The Planet Waves 1CRB6-10 is a 10-pack of premium celluloid picks in rainbow, heavy gauge. Celluloid is one of the most popular guitar pick materials today. Available in a wide variety of shapes, colors and thicknesses, celluloid is known for providing a natural feel and warm, fat tone. A man-made material, celluloid was first introduced in the early 1900's as a substitute for natural tortoise shell picks.