Free base nicotine can be quite harsh on the throat and can cause discomfort for some vapers. Nic salts are absorbed to the body far quicker than standard E liquid, so it provides a much quicker hit to keep your nicotine cravings at bay.
I bought these as they are made by the same suppliers as the Aisu nic salts. Unfortunately the flavour is not as good and although the nicotine content is advertised as the same (20%) they seem to have a much stronger throat his than the aisu brand.
My go to week long vape. Very good on coils