Les Duos concentrate is a French range of flavour concentrate created by Revolute (Laboratoire Cosmer) for DIY e-liquid, each combining 2 flavours, in the fruit, mint, fresh and gourmand families: strawberry and banana, raspberry and blackcurrant, spearmint and cucumber, madeleine and honey. Steeping takes 1 to 3 weeks in a 50/50 base. Made in France. Bottle size: 10 ml. Recommended dilution: 10%.