ExtremeMist PCS convertible hydration waist-pack provides easy access to your gear and hydration. Designed with convenience in mind, it comes with a zipper to attach to our "just add water" pack. When zipped to the pack, it redistributes much of the weight from your shoulders to your hips. It has a large back compartment with key clip, bungee attachment secures spare clothing items, 2 roomy side zippered pockets, dual bottle holders, and a mesh back panel for a comfortable fit. Product Highlights: • Compatible with PCS Ultimate Hydration pack (item number 126055)• Dual bottle holster• Zippered pockets for added storage• Small size expands to fit: 23â - 50â• Large size expands to fit: 27â - 58â• Made from breathable, water-resistant materials• Balanced weight distribution• Bungee cord ties for securing small items Redistributes weight from shoulders to hips for more comfortable carrying Compatible with PCS Ultimate Hydration Pack (item number 126055) Comes in multiple sizes and colors | Personal Cooling System (PCS) Detachable Hydration Waist-Pack in Blue