The main way the user was impacted by TPD regulations is the maximum bottle size limit of 10mL for any juice containing nicotine. Larger bottles are usually more convenient. 

Most vapers really don’t like having to carry around multiple 10mL bottles of the same flavour when one large one would do. Nic shots get around the 10mL bottle requirement without violating the letter of TPD law.

 They’re more cost effective, use less plastic and are a great option for sub Ohm vapers who use a lot of juice.

One of the biggest fears around new regulations before they were implemented was that they would stifle innovation. With every new flavour requiring an expensive and time consuming testing period, 

it was going to dramatically reduce the number of e-liquid varieties available for purchase. Nic shots changed all of this as they allowed businesses to continue as usual with regards to VG, PG, and flavour additives.

 The reason is each manufacturer only needs one general test for their unflavoured nicotine-bearing juice. 

Those looking to buy a 10mL TPD-compliant bottle of their favourite juices might not be able to find every flavour from every manufacturer available with the nicotine already inside it. 

However, manufacturers will still be able to offer every flavour from their juice lines in large bottles with a little extra space for the nic shot.

Pre-TPD, if you bought a 100mL bottle of nicotine-containing juice, you’d get a pre-mixed bottle full to the brim with your chosen flavour of e-liquid. With nic shots, 

they still come with 100ml of liquid but now, they’ll come in a 120mL bottle with some empty space at the top. This space is there to accommodate your nicotine shot (or two).

Nic Shot: Step By Step

Step 1: Get a pen and mark halfway down the height of the nic shot. All nic shots come in 10mL TPD-compliant bottles, so this halfway mark represents 5mL of nicotine-containing e-liquid. 

Once you’ve marked the halfway mark, mark again two more times, halfway above and halfway below the first. Each of these lines now represents 2.5mL of unflavoured nic shot.

Step 2: Figure out how much to add. Find a TPD nicotine shot calculator on the internet and input the size of your 0mg bottle, the strength of your nicotine shot (usually either 18mg or 20mg), 

and your desired nicotine level. The calculator will spit out a number. In the case of a 100mL bottle, 20mg nic shots, and a desired nicotine level of 3mg is 17.25mL of nic shot. This amounts to one full 10mL nic shot 

and slightly less than three quarters of a second, which you’ve already marked with a pen in step one.

Step 3: Unscrew your 0mg juice and slowly drip in your nic shot until you’ve reached your desired nicotine level as dictated by your online calculator in step two.

 It’s not a bad idea to test your e-liquid for flavour and nicotine potency throughout the mixing phase.

Step 4: Give the bottle a vigorous shake, test, and enjoy. Giving the bottle a little shake now and again helps make sure everything is evenly blended throughout.