Bottle Pouch Holder for Hydration Carrier Heavy Duty Sport Bottle Bag for Hiking Climbing Camping Top diameter: 3.5"; bottom diameter: 3.2". Multipurpose and versatility, fits most standard & small size water bottles, such as sport bottle, beverage bottle, stainless steel water bottle etc. Also great solution for carrying drinks, camera lens, umbrella, dogs treats, small fire extinguisher. And it can be used as drop pouch, snack pouch, feed bags to hold other items. Open top with adjustable drawstring which for different size bottle/container/can keep it from moving around too much and get quick-access to content. When tightening the drawstring, even you bend over with a water bottle inside and dont have to worry about the bottle falling out. Dotacty Tactical Water Bottle Pouch is ideal for hiking trips, camping, climbing, cycling, war game, hunting, fishing, riding, kayaking, motocross, even amusement parks and other outdoor activities. People always carry pack when hiking because they hate stuff in hands. Our water bottle pocket holder is a great addtion for sling pack, back pack, survival pack, day/go bagbag, tactical bag, tactical briefcase, range bag, rucker bag, lunch bag etc, frees up space for these bags, easy to access water source at critical moments.