Some Rubycon Aluminum Electrolytic Capacitors in radial lead configuration may have an “EFC” suffix attached to the end of the part number. “EFC” means that a PET sleeve is wrapped around the outside the capacitor case.
It is common in the industry to use PET sleeves, rather than PVC sleeve, to identify and mark the product. There are no electrical and functional characteristics associated with this sleeve. PET sleeves are an environment-friendly solution. The global regulation for REACH restricts the use of Phthalate(plasticizer) and Organostannic compounds(stabilizer), both of which are contained in PVC sleeves.