20mg is as strong as nic salts get in the UK, the legal maximum, and it's built for a proper throat hit. Where 5mg and 10mg ease you in gently, 20mg delivers a hit that's hard to miss, closer to the sensation of a cigarette than any lighter strength.
It suits heavier smokers, a pack a day or more, and anyone who's just made the switch and needs that satisfaction while they adjust. Best paired with a simple pod kit rather than a higher-powered device, since 20mg can turn harsh at higher wattages.