"Stability paired with stretchy goodness" is how we like to sum up this pack. The RFP hydration pack designed to keep you hydrated and comfortable during your outdoor adventures. The stretchy materials of the pack conform to your body and provide a comfortable fit, while the firm materials ensure a secure tension around your body paired with no movement of the fluids and gear you pack. We understand the importance of safety while adventuring, which is why the RFP hydration pack includes a built-in safety whistle on the front for emergencies and in the back a zipper-secure storage with key clip to keep your critical things in a safe place. When it comes to essential storage, we have outer chest pockets that are on top of the flask pockets for storing your phone and food. Shoulder pockets are perfect for electrolytes, nutrition and more, and the side mesh underarm pockets are great for those thinner food items. In the rear of the pack between the bladder storage and outer pocket, is a large open pocket great for stuffing additional layers. Built tough, this hydration pack is ready for any adventure. Whether it's a long hike or a bike ride, you can rest easy knowing the pack can handle anything you throw at it. Stay hydrated and comfortable on all of your outdoor excursions with the RFP hydration pack! Sizing: M/L fits a 36" to 44" chest - S/M fits a 31" to 37" chest (this size will be launched in late Summer 2023).