This product is Ethyl Maltol Crystals in USP 99.8+% Propylene Glycol (PG) Solution
Ethyl maltol Crystals is a very wonderful broad-spectrum flavoring agent, sweetener / smoothner and aroma improver, widely used in all kinds of drinks, wine, food, cakes, biscuits, canned cream candy, medicine and eliquids.
Brings richness and moistness to the table. Around 0.5-1% it adds body,moisture, and reduces sharp notes. Recommended 1-2 drops per 5ml eliquid, adding too much will mute flavor. It rounds off the flavors, and brings them out a bit. In other words, it reduces flavor intensity
If crystalization occurs the solution can be gently warmed-up and shaken to allow it to dissolve again in the PG.