MASON COTTON CASHMERE T-SHIRT - BLACKDETAILS Thanks, it's cashmere. The Mason is a cotton cashmere short sleeve sweater shirt, both ultra lightweight and warm for when you're between seasons. With a slightly tapered fit, the Mason is a sleek wardrobe staple that emphasizes ease. 70% Cotton 30% Cashmere Imported. CARE Dry clean only, do not bleach. Cool iron if needed. FIT Recommend ordering true to size. Front Body Length: 27 3 4" Model is wearing size M.