This a two part sweater: from the back it looks like two layers - one longer then the other, and from the front it looks like Ты are wearing a strapless вверх and a sweater on вверх of it . link
фото
sweater
вверх
This Teen Fashion фото contains
кардиган.
There might also be
пуловеры, slipover, пуловер, свитер, джемпер, джемперы, and свитера.