Lululemon Blue & White Beachy Floral White Porcelaine Cool Racerback Tank Top- Gently used with no flaws. Very crisp and clean colors.
There are no size tags or dots - It was purchased with numerous size 4 - 6 pieces, but I can not confirm the size. Please see measurements.
Has some stretch to it. 
One layer, no extra features like a bra 

Measurements done laying flat w/ no stretching & are approximate
Chest (underarm-underarm) = 15"
Length (shoulder-hem) = 28"