If your looking for the most undetectable to touch. than you will have to probably use glue. and have a very perfect attachment that is very flush against your skin. Its very hard to make hair systems totally undetectable to someone running their hands through your hair and not feel an edge or something weird. I have had extremely thin laces in the past from a company no longer in business that was undetectable to touch..

I suggest you just don't let people run their fingers through your hair. I mean everyone talks about this.. as a huge issue.. I usually have styling product in my hair and no one really wants to run their fingers through it lol. and if they do I just stop them and say i have a sensitive scalp. Or i dont' like people touching my head.