Unigear Tactical Hydration Pack Backpack 900D with 2.5L Bladder for Hiking, Biking, Running, Walking and Climbing Adjustable shoulder/chest straps. Will fit chest sizes from teenagers/kids with 27" up to adults (men and women) with 50" chest size. The chest straps make sure it doesn't bounce when you move; Whistle buckle for emergency Rugged 900 Denier Polyester heavy-duty construction with PVC lining, resistant to tears and abrasion; Hands-free hydration hose with bite valve, gently biting the valve opens up the flow of water REPLACEABLE 2.5L BLADDER: Includes a 2.5 Liter BPA free bladder which keeps you hydrated. It also keeps the water fairly cool. And include a wide screw cap so you can add ice cubes for an even cooler drink. Enough to get you through a day of hiking, cycling, running or biking Sleek and compact design: 19" x 10" x 1.5" in size and 22 ounces in weight; Two front pockets for carry your wallet, keys, phone, towel, smalltool, perfect for hiking, running, biking, walking 60 Day 100% Satisfaction Guarantee:If for any reason you are not 100% satisfied with this product, please contact customer service within 60 days, and we will immediately refund your purchase price - no questions asked Air mesh back and shoulder pad allow for airflow, comfort and thermal performance Adjustable chest and waist strap with tail holder more convenience for long journeys 2.5L BPA free wide mouth bladder The top pocket is a single pocket and contains a Velcro patch on the front The bottom pocket contains there mesh pockets to sort your stuff and one clip to put keys The main pocket is designated for the water bladder. It has bladder holder for both wide and small mouth bladder For wide mouth bladder, you can place it in the hole to keep it from sliding to bottom