Salt Nic Shot by Zap! Juice should not to be vaped on its own; it is a salt nicotine booster shot, designed for use with shortfill eliquids.
Adding this 18mg, 10ml salt nic shot to a 50ml, 0mg eliquid, will create a 3mg, 60ml e-liquid.
Adding 2 x 18mg 10ml salt nic shot to a 100ml, 0mg eliquid, will create a 3mg, 120ml e-liquid.
Salt nicotine interferes less with the liquids overall flavour and provides a more potent nicotine hit with less of a throat hit, for a smoother vape.