The flat rate padded envelope stuff nicely! Make sure you squeeze out all the air you can get out. LOL I have packaged up quite a bit of stuff the last couple of years. My family laughs at me. For larger packages, I use a nice heavy trash bag, bunch up the top around my vaccume hose and suck out all the air. Tie it real tight with a wire thingy. It is amazing how small it gets! Did this with a king size quilt, packed it into a box, taped it up good, and waited for the call when they opened that box and a quilt exploded out of it!! I have heard of using a straw to get all the air out of a baggie.