I bought adrafinil a few times, but after trying mods, I've stuck with that. Seems to last a bit longer and feels a little smoother, but that may just be because the modafinil is better quality. 50mg of modafinil feels like 200mg of adrafinil for me. I read somewhere that adrafinil is 2/3 the potency but I found it around 1/4. May have been the quality or maybe it's just me. They both do the job though. In a blind trial of equipotent doses, I probably wouldn't be able to tell the difference.