Pockets. And lots of them. We counted 13: zippered, Velcro tabbed, meshed, the lot. The Megamouth is great looking too - slim and minimal when compressed, generous (18 litres) when expanded.
Web straps keep it stable whatever the load. There's an emergency whistle in the buckle and a magnetic holder for the bladder hose, again by Nalgene. A bungee strap takes care of spare layers, while the external mesh pouch can house a helmet. There's an easy to grab handle, reflectors and LED strap - you won't get a more feature packed bag for the money. The back is long and flexible, with sectional padding to let air circulate - we felt the seam round the thin lower padding was more prone to rubbing the vertebrae when badly packed, though using the bladder helped. The long length is best for medium to tall riders, as you may notice it touch your helmet when deep in the drops.