Most of these bags are BIG. Most LOTs bigger than a standard comforter. 
Study plastic but the plastic sliding closing tabs tend to fall off easily. Needed a bit of extra work to close. The hand pump worked to take air out, it just took a LOT of time for the large and jumbo bags. I had to switch to my vacuum hose option. Once closed, it seemed tight. The bags get really, really "hardend"....weighed actually more than outside of vacuumed pack. If you are travelling keep this in mind!