Either size 4 or 6. Doesn’t say on the tank. Measurements: Armpit to armpit about 14” Top of strap to bottom of tank about 25” Taken laying flat. This is a very light, stretchy racer back tank. Draped in the back with a crop top underneath. Key features Vitasea fabric blends Pima Cotton and high-stretch LYCRA® fibres that means great shape retention and a super-soft feel inner layer fits snug for coverage curved hem makes tuck-ins a breeze during Down Dog designed not to shrink so there are no surprises on laundry day imported Fit + function designed for: yoga, to-and-from fabric(s): Vitasea fit: slim shelf bra: no support: none coverage: low length: hip