After using the bags that were supplied with my prolux, I purchased these OEMs, to ensure the proper fit. I was surprised, actually, when I first opened them - since they were huge compared to what was supplied with my vacuum. It's a pretty small unit so I didn't expect a large bag to be with it. I only use the vacuum for the upstairs, which does not get as much use - so I was ok with the small bags. But these big-boys are going to last a long time, for sure! I bought two packs - they may last my lifetime. :-)