Use the Shop-Vac® foam sleeve for picking up wet messes when used alone. The foam sleeve is also required when using reusable dry filters. The approximate size of the foam sleeve is 8 in Dia and 6-1/2 H. The foam sleeve is required unless you are using a cartridge filter. It fit's Shop-Vac® brand wet/dry vacuums 5 gal and above (except 5 gal portable model H87S, 5 gal HangUp®, 5 gal wall mount and 6 gal long life model P12S vacuums).