Electrolux S bags can come in may verities.  Electrolux S Classic bag is the original standard paper bag, the Electrolux Clinic bag is the anti-allergen bag that has high filtration and is ideal for allergy suffers.  There is also a anti-odour bag which is ideal is you have a pet, this bag will help to eliminate the pet smell coming through the exhaust of the vacuum cleaner.  There is also a generic bag which will do a similar job as the Electrolux S classic bag, but has a slightly different paper quality, and is about half of the price.