I was searching around for info about Evans Waterless Coolant and some people (on the net) say it is just pure 100% propylene glycol
It has a higher boiling point than water but doesnt lose its heat as well,so your coolant fans tend to run more often.
They also recommend a prep fuid as hanso mentioned,it is suppose to absorb the last remaining traces of water from the system.
However,as propylene glycol also absorbs water me thinks the prep fuid is the same as the coolant they are selling you.
Im not saying dont buy it ,just do some research and make your mind up.