In the search for additives that make liquid feel cold, we ended up making our own.
Again our business partner was kind enough to provide us with enough samples of additives from which we could pick one with best characteristics.
This is not koolada, menthol or a similar product available on the market. We had some users who don't like koolada because of bitter taste (they could taste it) or allergic reaction when it comes to direct contact with lips and tongue. That is why we found this component very well known and researched 100% safe to use.
This product comes in 10ml bottle with pipette, use it 1 to 5 drops per 10ml of e liquid to cool it down.