Flavor West flavour concentrates are Naturally and Artificially Flavoured. Made in the USA & Rebottled by Vapour Depot in the UK. Available Sizes: 10ml, 30ml, 100ml Recommended Mix (Single Flavour): 5% Recommended Mix (Multiple Flavour Recipe):1% Requires mixing with Vegetable Glycerin & Propylene Glycol before can be vaped. FW Sour Concentrated Flavouring We know that all you really want is a delicious tasting, high quality food grade concentrated flavoring, and thats precisely what we bring you. Sour flavor come with a note of Malic Acid. This flavor has a sour and salty taste that makes it pleasant in recipes.