This range of flavoured concentrates from Hangsen have been specifically designed for use in e-liquid production. It's worth noting that some brands of concentrate are food grade only and therefore they aren't always suitable for vaping.
To prepare your own favourite flavour of e-liquid, just grab a 10ml bottle of unflavoured liquid from the drop down menu above and pick your flavours to the right. The more you add, the stronger the flavour, but I'd suggest you add about 8 drops of flavour concentrate to each 10ml of unflavoured liquid, give it a good shake and leave to steep (usualy for arounf a week if possible to really bring out the flavour).
Concentrates can then be blended to make that flavour special flavour you just can't get at your local store... like Chocobanana (chocolate plus banana)... or Minty Lemon... need I go on?