The BlackHawk HydraStorm Barracuda is a hydration pack with kit carriage ability that is perfect for short missions.

The Barracuda is a low profile pack that combines a protected external fill cap and a large pocket to put kit in. It has a 3 litre capacity which should keep you going for hours, even in the heat of somewhere like Iraq.
 
The protective flap and pocket are covered Blackhawks patented S.T.R.I.K.E.™ system for modular attachment of Blackhawk accessories.

It's a good sturdy bit of kit that should keep you going for years.

Features:
Drink system protected by Microban® antimicrobial treatment.
Market proven bite valve and patent pending quick disconnect system.
Comfortable, fully adjustable quick-ditch harness. IVS™ molded back panel superior for comfort, stability, and airflow.

Top Tour Tip: Using the D rings on the side of this, you can cable-tie it to your ops vest, meaning you don't have to put your arms through the straps and it's held firmly in place.