Natural symmastia or breasts that touch in the middle (AKA "kissing breasts")

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I particularly like the look of natural breasts that have no gap between them even when not wearing a bra. If the breasts just barely touch at the cleavage line, they're called "kissing breasts", but with some girls there's no cleavage line at all and the skin in the middle isn't attached to her chest wall (sternum).

A good example of this is Jo Paul:
http://www.freeones.com/html/j_links/Jo_Paul/


Note the way the undersides of her boobs "join" in the middle.