Gray striped racer back tank maxi dress S / XS

Dark and light gray tank maxi dress with knotted racer back. I received this as a gift but only wore it twice so selling it now in hopes it'll get worn more! Though it's a maxi dress, I'd say it hits at my ankles rather than at the floor (I'm 5'6''), so perhaps it'd be the perfect length for someone a couple inches shorter than me. Jersey type material, Size S, but it's pretty form fitting, so XS could fit also. NOT ZARA, I just put that for exposure (: This is an unknown brand.