Quick view Douglas Products Douglas HTF Inhibited Propylene Glycol MSRP: $121.80 - $638.28 Douglas HTF Inhibited Propylene Glycol in 1 Gallon Containers Recommended for: Block Ice MachinesCirculating Beer SystemsClosed Water Loop Refrigeration SystemWood Boiler SystemClosed Loop... MSRP: $121.80 - $638.28 Quick Add Add to Wish list