Semi-flex polyethylene tube. Good for all tube flies and cold water conditions. The O.D. is 1/10" (use 0.062" pin) and there is a great choice of colors. Each package includes 10 tubes which makes over 4 dozen 1" tubes, plus hookholder tubing. The 'retro' assortment includes clear and 4 colors: green apple, bubblegum pink, cream orange and grape purple. The 'hot color' assortment includes clear and 4 hot colors: bright green, fl. pink, fl. orange and fl. yellow.