Filtex Bag 12 gal (Airvac) Central Vacuum  Lrg Capacity (4)

Filtex (or Filtrex) and others. Replaces all Filtex bags about 18 inches tall and taller. Filter S-310. Top of bag has 1.25 inch round cardboard lip and 13.5 inch total diameter. (The variation over the years is due to changing bag manufacturers.)
Also fits some units made by: M&S, M & S. .

Filtex Bag 9 gal (Airvac) Central  Vacuum   (4) 

Filtex (or Filtrex) and others. Replaces all Filtex bags between 14 and 18 inches tall. (The length variation over the years is due to changing bag manufacturers.)
Also fits all or some units made by: Brute, Central Vac International, D & R Vacuum, D&R, Star.
Top of bag has 1.25 inch round cardboard lip and 13.5 inch total diameter