IYunithi yeFayibha yokuSebenza eYomeleziweyo (EPFU) bubukhulu obuncinci, ubunzima obulula, iyunithi yefiber ye-sheath yangaphandle eyongeziweyo enekhonkco eyenzelwe ukuvuthela kwiinyanda zetyhubhu ezincinci ngokuhamba komoya. Uluhlu lwangaphandle lwe-thermoplastic lubonelela ngezinga eliphezulu lokukhusela kunye neempawu ezigqwesileyo zokufakela.