This product is Ethyl Vanillan Crystals in USP 99.8+% Propylene Glycol (PG) Solution
Ethyl Vanillan Crystals is a very wonderful broad-spectrum flavoring agent, sweetener and adds a hint of vanilla to eliquid, widely used in all kinds of drinks, wine, food, cakes, biscuits, canned cream candy, medicine and eliquids.
Around .5%, 1% usage is the norm, maximum will be around 2.5%-5%. Never go > 5% since taste will be muted, less is more using EV
Recommended 1-2 drops per 5ml eliquid
If crystalization occurs the solution can be gently warmed-up and shaken to allow it to dissolve again in the PG.