A glimmer of hope. RIDGID, Home Depot, may have some answers..The Hi Eff baag I use in my 5 gal Shop Vac is P/N 90671..Got looking @ Ridgid, inspired by yorkdude, and found the following.
Overview
Model # 12323 Store SKU # 1000803653
The Filter Power model 12323 is a High Efficiency disposable replacement filtration bag designed to fit most 5-9 U.S. Gallon Wet/Dry Vacuums. This High Efficiency filtration bag is for DRY pickup only. Our item replaces VF2004, VF3503 bags and also Mastervac* 054-0003, 054-0150 bags. It is designed to fit most 5-9 U.S. Gallon Shop-Vac* and Genie* Wet/Dry vacs, Rigid* WD0670, WD0970, WD0975 and Craftman* #97411. Each pack contains 2 bags. *Mastervac is a registered trademark of Canadian Tire Corporation, Ltd. All rights reserved. *Shop-Vac is a registered trademark of the Shop-Vac Corporation. All rights reserved. *Genie is a registered trademark of Genie Corp. All rights reserved. *Craftman is a registered trademark of LDC IP, LLC. All rights reserved. *Rigid is a registered trademark of Rigid Inc. All rights reserved.
Ideal for trapping dust and dirt in bag
Keeps the inside of the Vac drum clean and allows for fast and easy removal of debris from the tank
Includes 2 High Efficiency filtration bags
For use with most 5-9 U.S. Gallon Wet/Dry Vacs
Improves vacuuming efficiency
Designed to fit Wet/Dry Vacs using style H 90671
Mind you, this is from Home Depot Canada website. Surely it's the same in the US..