basically, if i fill my suitcase to the brim without using the compression bags, take those clothes and put them in the compression bags, compress the air out and put them back into the suitcase, my suitcase is now only 1/3 full.  plus, for as much as i travel, i'll probably have these for 50 more years.  i guess if these are used frequently they may tear but they're pretty durable.  I recommend these since you can manually get the air out, you don't need a vacuum or other special connector.