5mg Nicotine
5mg is the step down. It is where people go when 10mg has started to feel like more than they need, and it is the lightest salt strength most brands bother making.
It suits a light smoker, or somebody a long way into cutting down. If you have just put the cigarettes down it will probably feel thin - 20mg is the usual starting point off a twenty-a-day habit.
Because it is a salt it still lands smoothly, so the lower strength does not come with a harsher hit.