Tennessee Valley Apothecary's concentration blend "Sharp As A Tack" is a convenient, ready to use pre-diluted roll-on bottle of a carefully researched synergistic blend of essential oils that are designed to support your efforts in remaining calm and focused during study or the task at hand. * This product is typically used by applying to the insides of your wrist similar to how you would apply perfume or on the base of the skull on the back of the neck.