Large main compartment with hydration reservoir COMFORTABLE, ERGONOMIC DESIGN. High Sierra features a comfortable, ergonomic design with this awesome adult hydration backpack; padded back panel and shoulder straps with air mesh material help keep shoulders comfortable and your back cool and dry LIGHTWEIGHT AND STABLE: HydraHike running hydration backpack has an adjustable sternum strap and webbing hip belt to help secure the bag on your back; adjust these straps to fit your size; light enough to use as a kids' hydration pack SAFE TO USE FOR NIGHT CAMPING: this hydration pack features reflective details on the front and back which help keep you safe while out in the dark; HydraHike is the perfect camping hydration backpack MADE TO LAST: this outdoor hydration pack is coated with 600D poly with nylon ripstop making it strong and durable; enjoy many exciting hiking trips with this water hydration backpack BPA-Free Hydration Reservoir included.