Hard seltzer, adult seltzer, mature seltzer, spiked seltzer and hard sparkling alcohol water is a type of highball drink containing seltzer (carbonated water), alcohol, and often fruit flavorings.[1] In the US the alcohol is usually made by fermenting cane sugar or malted barley.[1] Hard seltzer products outside of the US have been found to use either neutral spirit,[2] or fermentation of fruit.[3] The alcohol by volume is around 5%[4] and the calorie-content is relatively low, derived almost entirely from fructose.[5][6]