These long tanks are all size Large!
The Long tank is exactly that....a long tank.  It's a great base layer year round.  Fits snug to the body, and the hem hits just below your bum.  
Looks great over pants, leggings, or long skirts.  Could even be a stand alone tank dress.  Have fun layering looser shirts or sweaters over top.
Made with a slightly thicker 100% organic cotton jersey (same fabric that I use for the Star Gazer Cropped Tank), with a touch of spandex.
Shoulder to hem is roughly 31"