Packmates are air-tight bags that you pack with clothes, pillows, etc. Once you stuff them full, you zip it and "squeeze" out all the air. This literally flattens it about 2/3. They seal in moisture and odor. There are lots of infomercials on them and they really do work. Once you zip them, some people roll them to get out "extra" air, which really flattens them to a pulp. They come in different sizes (small up to jumbo-big enough for comforters), People also use them to store away stuff at home (like off-season clothes and bedding). It really allows you to store more stuff and take up less space. (I ought to know-my husband was a product specialist host on QVC and sold them-so we had plenty to try out) They worked great for my sand-filled/wet water shoes and bathing suits.