Any fiber that is man-made and created from chemicals. Examples of synthetic fibers are nylon, rayon, orlon, and polyester. There are three types of synthetic fibers used in the manufacture of wigs and hairpieces. They are polyester, acrylic, and polyvinyl chloride (PVC). The quality and life-expectancy of a wig fiber is usually measured by its similar appearance to human hair and also by its tolerance to heat. There are many different levels of quality in synthetic fibers, even within one type (such as Kanekalon). Some fiber is very cheaply produced, has an unnatural sheen, and will not tolerate heat well. Other synthetics appear much more like human hair, and will tolerate more heat, sometimes over 300F degrees. This accounts for the wide variation in the price of synthetic wigs.