I have used thousands of dust bags over the years as a carpenter repairing many houses a year. I bought these bags to save on my Fein2 because I got more for my money. I have a HEPA filter on my fine and I'm glad I did. These bags let a lot of fine dust through. I was surprised how much. I mainly vacuum fine wood dust from sanding wood and drywall. I would not recommend these bags. I've gone back to my more expensive Fein bags and the difference is very noticeable.