The red (and blue) things are referred to as a "dendrites" in the DVD commentary. They earn credits working merely to buy them over and over again. They serve no function or other purpose.

First couple times I saw the movie when younger, I thought it was some sort of container for their daily drug supply! Probably because we see another fellow arrested desperately clutching his dendrite as he's taken away.

I always thought "consumer" meant something else, (as in the SE's don't fit my consumer) but the urinal like device in THX's apartment must be it.

Someone ankle deep in dendrites because they can't dispose of them, while still dutifully buying more would have been really funny. ;)