Features Center wall for a slim shape and increased stability Roll-top slider seal closes tight for a leakproof seal High-Flow Blaster bite valve self seals after each ship and also features a twist on/of bar prevents leaks when not in use Plug-N-Play connect system lets you easily disconnect the drink tube (an auto shut valve prevents leaking) and removes the reservoir from your pack for convenient refilling Made of ultra-durable, abrasion resistant TPU & RF welded seams for superior durability and elasticity Can be frozen or filled with hot water (min. temp -20 °C / max. temp 50 °C) > Safe and reliable, 100% BPA & PVC free Outer Shell: Thermoplastic Polyurethane