I don't have a great way to authenticate that this is actually 99.9% Propylene Glycol, but it does behave like it should. I first tried it circulating in a cooling system I was going to use to reclaim waste heat from a diesel heater's exhaust. It circulated fine in the system, it is a little more viscous than straight water but that is to be expected. I then put it in our freezer, the approximately 50/50 water/propylene glycol blend was fine in my freezer at -18°C, no signs of ice crystal formation so that is a good sign (it should be good down to about -35°C but I don't have a way to test that at the moment, not yet the dead of winter).Last property I tried was taste - since this is food grade I figured that should be safe. It tastes like propylene glycol should - I guess at some point I must have accidentally tasted antifreeze because the taste was familiar and associated with antifreeze. So it does seem to be propylene glycol, the volume is as indicated (well, one of the 4L or 1 Gallon is slightly wrong since a gallon is 3.785L), it arrived in a sealed container - all good.