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.

I use extendabond mini tape tabs with lace and glue and there is no bump for me. If anyone ran their fingers down the back of my head they would feel absolutely nothing. I feel nothing myself. But going up the way they might feel the edge of the lace if they were really digging their fingers in. But people don't generally run their fingers up other people's heads and if it's an intimate encounter tell them you don't like it, sensitve skin etc.. They will not be upset!