The blend portion of Protex C can range from 20 to 85%, depending on its blend partners. Most dual hazard fabrics will use Protex C fiber in their blend. The C fiber is typically sold in a 1.5 Denier x 38 mm cut staple length. Yarns blended with Protex C will normally be finer and are typically stronger than yarns spun with Protex M, due to the lower Denier of Protex C.
ArcWear does not recommend one fiber over another but many of our clients have asked this question. When specifying a fabric that does not have a strong brand things like this can make a positive or negative difference.