HOW TO GET THE FILL 2 LITER'S IN -- Hold with opening face up as you fill weight of water puts bag down. PRESSURE-TOLERANT -- Built out of a really sturdy material, It can withstand pressure excellently. Double sealing side does greatly improve durablity. It can provide a wholesome flow for easy drinking, keeping you hydrated when biking, cycling, hiking, or running!. HIGH PERFORMANCE DRINKING VALVE -- Easily accessible ON/OFF valve. Soft mouthpiece make you bite down on it easily. Water flows out of the valve smoothly so that it does not take significant effort to get water into your mouth. The water flow can be controlled by biting. With design of tube connector, it's easy to take off and install the tube. 2L WATER RESERVOIR -- 14.2" x 6.8" Water Bladder is a universal fit for most packs. It is made of premium material, providing you perfect drinking. When the hydration bladder is empty, it can be folded. So it won't occupy much room in your backpack. LARGE OPENING -- Hydration Bladder has large opening, which is easy to fill with water. Also, the water opening is big enough that you can put your hand through to clean the inside. Fill cover is attached to the bladder so you don't have to worry about it exposed to the air. High performance seal does it good job in unscrew and fill up securely.