With the fox oasis hydration pack you can take all your essentials with you and be prepared for anything this super sleek 2 liter oasis hydration pack features plenty of storage options in a low profile unrestricted design fox oasis hydration pack features eva molded back panel with airflow channel allows air to circulate and regulate moisture hydrapak 2 liter reservoir with slide top large opening for easy filling cleaning 45 angle bite surge valve high flow with a twist shu