Sirena Rib Tank Z SUPPLY Sirena Rib Tank Z SUPPLY Sirena Rib Tank Z SUPPLY Sirena Rib Tank Z SUPPLY Sirena Rib Tank Z SUPPLY Sirena Rib Tank Z SUPPLY. The Sirena Rib Tank from Z Supply is meant to be layered. Made from a cotton spandex rib knit fabric that was given a special wash for extra softness. This tank is the perfect layering piece, regardless of the weather, thanks to its sleek silhouette. Features: Scoop neckline Bra friendly thick straps Made of ribbed knit fabric Fitted silhouette Bust: 28. 5" Length: 22" Need an outfit for a brunch with friends? Wear this tank with skinny jeans, ankle heeled boots and long cardigan for an edgy look. Model is wearing a size Small