Our best-selling bottle, the Little Big Mouth 21oz Bottle takes a revolutionary design and shrinks it down a bit. Its conveniently shaped and absolutely leak-proof. It has a tight-sealing Big Mouth screw top thats ultra-wide for adding things like ice or your hydration powder of choice. This piece also provides an incredible level of water flow thats up to 50% greater than the competition. Meanwhile, we gave the bottle a flexible, ergonomic design that grips to cages and fits easily in the hand, while the bottles construction is made from BPA-free plastic thats 100% FDA food-grade approved.