I saw a post somewhere recommending PackMate bags, so I ordered their "family pack" for $39 online. Just received them. Am I missing something or are these bags just simple ziploc bags with a small air opening at the other end? Can't believe I spent $39 for ziploc bags. Do they really work? They claim to reduce your packing space considerably by squeezing out all the air in these special bags. I know I'm a newbie, but now I feel stupid too!