Ok, here's what I did with the space bags.
i bought the under bed storage bags (sold on QVC) since they are in fabric "boxes".
In one bag I put batting like the warm and natural that is NOT in plastic manufacturer bags. It sucked down and I zipped the outer bag shut. I noticed after a day or two the contents had increased in size but was not causing the fabric top to begin bulging.
In the other bag I put batting that comes rolled up in a plastic manufacturers bag. I did open the individual bags but left the batting inside. It did not suck down as tightly, nor did it stay down as well. The zipped shut fabric bag began to bulge by the following day. I think the fabric outer bag has made a little difference in how much the bag will expand. I will keep them, because they stack under my long arm table so they are out of the way.
I have a huge roll of warm and natural. My husband got a long piece of 4" PVC pipe and 2 car jacks and made a stand for the roll. He put the pipe through the center of the roll of batting and then set it under my quilting table on the two car jacks. That works ok. It isn't as secure as the fancy roll holders you buy with the longarm machine, but it works just as well.

Thanks everyone for helping me.
I hope this is helpful to someone out there.
Isn't this a great place for getting good advice!

Good to know. I bought a bunch of batting at the last JoAnn's sale and now it's covering the closet floor. Of course, the cats like it to sleep on!

I had not thought of that but I am certainly going to try it. I have batting under tables all over and this would be a great way to control it.

hello, i have discovered that changing the way i filled my original space saver storage bags made them stay flatter.
i needed batting for a quilt so i took a bag from one of the space saver "suitcases". while the "suitcase"
was open, i took all the batting OUT of its original manufacturer's plastic bag. then i put it back in the space saver and
sucked out the air. the whole contents went down much flatter than it had before and stayed down.
i think the original manufacturer's plastic bags didn't let all the air out and that is what kept that "suitcase"
bag from really getting flat.

Wonder if there is a 'good-better-best' quality/brand of the space saver bags?

I have purchased the space bags as well. I did not have success. I put my MILs crocheted afghans into them; but within minutes the air is back. So did not save me space. Would love to know if I am doing something wrong. Thanks, T

I don't know about quality of any particular brand. I like the bags with the softer 'zipper'. I also like the looks of the bags with the fabric covering. I liked the size and look of the 'under bed bags' since they would be visible under my quilting table.
I have also found I can suck out air and store small projects and fabric in Hefty's Jumbo Zip Top bags. I fill it up, zip it almost shut (leave about 2-3 inches open) then I lay it on a table top and lean as much air out as I can. If leaning on it doesn't work, I roll it up to get air out. They stay pretty flat, too, so I guess the most important thing is to get the air out and shut quick.

I have tried the "space" bags a few times for storage of clothes, blankets, etc. Every time I go to get them out they are full size again and my sweaters all smelled and had to be cleaned. As far as I'm concerned, they are a waste of money and don't work! Just my experience hope someone else has better luck.

My vacuum hose does not fit the opening on the space bags but I have heard most of the same comments as on here, they fill back up with air and don't stay flat. For bags that won't stay flat, I would use the Target under bed plastic zipper bags. They are huge and really sturdy, and much cheaper than space bags.