E-PTFE stands for ‘expanded’ PTFE. Before PTFE yarns are cut from a PTFE film, the polymer structure of the PTFE film is stretched monoaxially or biaxially, depending on the manufacturer, in order to give the yarns higher strength. Manufacturers of PTFE yarns frequently use the supplement ‘e’ in different ways. Even if it is not listed. The fibers are always made from an expanded film. Today the ‘e’ is used more for marketing purposes than for technical reasons.