MYLAR – package of 5 pieces – 18inx30in. Looking to add a little more sparkle to your Holidays this year? Get the beauty and sparkle of a metallic thread without all the hassles or expense! Metallic thread can be expensive, troublesome and itchy. Mylar makes your regular Rayon or Polyester embroidery thread look like you used a specialty thread such as metallic. It gives it a subtle, elegant sparkle. Machine Washable & Heat Resistant. Mylar sheets are used in all of the Purely Gates Embroidery Design Patterns.