S'well Tumbler with Straw 24oz in Black. S'well Tumbler with Straw 24oz in Black. 18/8 stainless steel. Features Therma-S'well Technology with triple-layered, vacuum-insulated construction designed to keep beverages cold for 18 hours or hot for 5 hours. Thin, wide-mouth rim for easy drinking. Slide-open lid and flexi stainless steel straw for easy sipping. BPA/BPS-free. Perfect for iced teas, fountain drinks and smoothies. Top-rack dishwasher safe. 24 oz. SWER-WA59. 14824-A21-73401. At S'well, they're a design company for good, best known for creating the first, reusable fashion hydration accessory. Founded by Sarah Kauss in 2010 to help rid the world of single-use plastic bottles, they believe something as simple as buying a beautiful reusable bottle or bowl can make a big difference. Whether it's their original, iconic 17-ounce bottle or their latest innovations in food, barware and accessories, everything they make is designed to perform and offer more ways to help you use less.