Go Staks are a smart and sleek advancement in portable nutrition. Durable jars secure tightly to carry powders, vitamins, supplements, snacks, and more. Whether you pack pre-, intra-, and post-workout supplements to the gym, or simply need a versatile system for snacks and small items, the Go Stak has you covered. The BlenderBottle Classic revolutionized the industry back in 2004 with its leak-proof seal, iconic design, and the patented BlenderBall? wire whisk. Now, years later, it"s still the best-selling shaker on the market. Why? Because it works. ? Twist n" Lock? System connects jars with ease ? Secure Seal for worry-free portability ? Durable Eastman Tritan? material resists stains & odors ? Fits Inside your BlenderBottle Classic? or SportMixer? ? Mix and Match jar sizes for a perfectly customized stack