Michael Lauren Mason Basic Rib Tank in Black. - size L (also in XS) Michael Lauren Mason Basic Rib Tank in Black. - size L (also in XS) 94% rayon 6% spandex. Dry clean recommended. Rib knit fabric. MLAU-WS455. ML 6005 RIB. The designers behind Lauren Moshi take their comfortable pieces to a new level. With Michael Lauren, expect a range of lounge-worthy basics for the girl who likes to relax in style.