Hi expriest... I`m totally in the dark on this..it`s just not a thing which ever really crossed my mind.. I never thought about it on a kind of [not being offensive now ] `macro`level.... I would have assumed the factories would try to match the hairs from your hair-sample ? Maybe it`s not something which was ever really an issue for most wearers ? I`m just guessing. I`m [again ] not being `smart`with you but if your own is so thin/fine now would you be better off just going full-cap? I know wearing full-caps brings other issues but there are up-sides to it too...the main one for me, being not having to worry about either color-blend or [in your case] texture/diameter of hair...I guess if you still have a reasonable amount of your natural hair, well, stay with toppers for now.... maybe if you ask for a better diameter-match with an order next time, they will do their best to oblige you? Cheers for now, Paul.