We wear it alone, next to skin on crisp fall mornings, or we layer it as fall moves to winter. We love it for 9 months a year. Lightweight sweater knit makes for a great thermal piece, but the poly/nylon/spandex blend makes this sweater a top performer. Our Synergy™ yarn wicks and warms even when wet. Only @ T9. XS(2), S(4-6), M(8-10), L(12-14), XL(16).