Felji Shop-Vac 90398 Small Cartridge Filter Type AA Wet Dry Vacs 903-98 90399 Replacement Shop-Vac Lowe's Wet/Dry Vac H87S550A Vacuum Cartridge Filter The Shop-Vac Small Cartridge Filter is designed to combat your toughest challenge. The approximate size of the Shop-Vac Small Cartridge Filter is 5.75 inch diameter and 5 inches high. Overtime filters get clogged up with dirt impeding the airflow of the vacuum thus losing suction and performance. We recommend replacing your vacuum filters every 3 to 6 months for best performance. Easy to use; Fits Shop-Vac brand 1-4 Gallon* wet dry vacuums (except models J200A, K250, KA450, L250, MACM-250, MACS-200D, MC150A, MC12V1800, 1x1, Micro, HangOn, HangUp Mini, All Around, All Around Ez), 5 Gallon* portable model H87S, 5 Gallon* HangUp, 5 Gallon* Wall Mount and 6 Gallon* long life model P12S vacuums.