Hydration System TPU Slider Lock Internal Baffle 2L/3L | Waterflow IzotubeStop settling for mediocre hydration. The Waterflow Izotube is a high performance hydration engine engineered for athletes who push boundariesfrom high altitude thru hikers to competitive ultra runners. Unlike standard reservoirs made from flimsy PEVA, the Izotube is forged from heavy duty, medical grade TPU. This isn't just about durability; its about providing a BPA free, odorless experience that ensures your water tastes like water, not plastic,