Quite a low amount compared to my son's usual dosage (brand unavailable at the time), but seemed to work when we doubled the dosage. NAC has been pivotal in reversing some of the symptoms my son's neurological condition.
Not sure if smell or no smell makes a difference, but this one works and doesn't smell. I take NAC for sulfite intolerance caused by oxidative stress.
One with every meal, sometimes I need one extra for sulfite-laden foods. For half a clove of garlic one is fine.