The North Face make no-nonsense, well thought-out products and the Hammerhead pack takes advantage of being designed around trail runners as well as cyclists.
A frame with mesh backing supports the pack and holds it away from your back for ventilation - perfect for sweaty summer riding. A slight downside is that you lose some pack space, although at 12 litres, there is still plenty of room.
Externally there are two pockets - sized to take water bottles - one deep open pocket that's good for a pump or similar, and LED mount, and both waist and chest straps. The waist strap could do with being thicker, but the chest strap is perfect - even having a magnetic patch for the hose to stick on, instead of waving around irritatingly.
There are three pockets for the bag - one for the bladder, a main pocket perfect for clothing and longer tools like pumps, and a smaller organiser pocket with straps and zipped pockets for all your gubbins. The bladder is a simple 3 litre affair with removable hose and lockout.