From mountain biking to hiking, it’s essential to stay hydrated before, during and after physical activity. But when your body is on the go, it’s not always easy to carry a water bottle. Fear not. Hydration backpacks can sustain you with an adequate amount of liquid held in an insulated reservoir that keeps the liquid cool and your hands free. With a capacity of  between 30 and 100 ounces, hydration backpacks have adjustable straps to fit your body, additional storage pockets and vents for breathability.

Here are the specs on three popular models.

Camelbak Lobo 100

• Holds 100 ounces of liquid
• Kids mini design holds 50 ounces of liquid
• 90-degree bend to fit back properly
• “Big Bite” valve makes it easy to drink while performing activity
• Insulated sleeve keeps liquid cool for hours
• Ventilation on the back

NV Back Panel

• 180-degree ventilation pods and straps move in concert with your body during activity, regardless of how much you are carrying
• During activity, each pod forms to balance the weight of the liquid, thereby stabilizing your movement
• 3 airflow channels for extra ventilation
• Cargo organization, helmet hooks and rain covering

Camelbak Classic 70

• Holds 70 ounces of liquid
• Best for light packs and day trips
• Contains stash pockets for essentials like wallet and keys
• Lightweight and superb breathability