Electrolux
The first(1952-54) of many to use the same bag.Type C.Can be found at Electrolux/Aerus branch if you still have one,any vac store,many dept and even some grocery stores.Just try to get a quality bag with 4 layer filtration.
Your model would have also used an after filter until bags were improved.Remove rear cover with thumb screw in center of blower opening.If it does have used dirty filter discard for better air flow.
Bags,hoses,attachments and even parts are easily available when needed.Happy Vintage Vacuuming.