Hello mulder, it`s hard to be any way specific or give specifications as these individuals are `wearing`their own hair -- obviously the likes of Jake, has a fine head of hair, and it would be hard [in my opinion ] to replicate that, unless you were to wear a full -cap. The guy in the first pic would be easier to copy I think but you can`t really say they have a certain `` density`` as such as it`s the hair they happen to have --it`s not like you look at a system [knowing it to be a system] and can say it`s x,y,or z density -- I hope you follow what I`m trying to say.
In the case of a person considering wearing, if /when they post a pic, you can look at their remaining hair, and give an opinion on what degree of density would most likely suit them for blending -in purposes,rather than looking at a person with all their own natural hair and say they have a particular density --- am I making any sense ? Maybe not....hhmmmm!! LOL Paul.