The problem isn't "portable" as in "take it with me when I'm spending a day elsewhere" - it's "portable" as in "am I attached to this pump sitting at a table with one hand on each bottle/cup/breast and unable to move, read, knit, make lunch for the kids, etc" as opposed to the theory of the Whisperwear, in which I could tuck the things inside my bra and walk around, no tubes/powercord/hands, and do anything except nurse.