TFA flavour concentrates are Naturally and Artificially Flavoured. Made in the USA by The Perfumers Apprentice& Rebottled by Vapour Depot in the UK. Available Sizes: 10ml, 30ml, 100ml Recommended Mix (Single Flavour): 3% Recommended Mix (Multiple Flavour Recipe):1.5% Requires mixing with Vegetable Glycerin & Propylene Glycol before can be vaped. TFA Sour Concentrated Flavouring A large range of flavours for use in various applications such as: Baking, Candy-Making, Carbonated water (soda flavors), and many other applications that have fun with flavors!. This is a sour note that can be used with other flavors for a \"sour-candy\" effect.