Is there such thing as a small diameter Cat 5 cable?

I'm trying to find bulk cat 5 cable that has a smaller diameter then does the standard type. I've seen the the thin flat types of cable before but am not looking for one that is flat. I know there are certain requirements for a Cat 5 cable such as conductor wire diameter, etc. But it seems to me that standard cables have a loose fitting jacket that contains the conductor pairs and if this jacket were to fit more snugly the diameter could be reduced. Does such a cable exist?