SHOP VAC Replacement Retainer Nut for Small Cartridge Filter 3183000 Outside Diameter: 4-15/16" (4.9375") Manufacturer Part No.: 318-30-00 Genuine OEM Replacement Part For use on: 4 Gallon Floormaster, All Around Plus (not All Around), 5 Gallon Heavy Duty Portable, and the Hang Up Vacs (not the Industrial HangUp Vac). For use with Shop-Vac Small Cartridge Filters measuring approximately 5.75 inch diameter and 5 inches high.