As well as the main compartment the 3N1-30 has a separate top compartment big enough for a packed lunch, an anorak and your weak lemon drink, with a few small pockets for pens, a mobile phone and other bits and pieces. There are also two small zipped outer pockets that are ideal for loose change, car keys and other small items.
The bag is designed to fit airline carry-on baggage size requirements, and will fit into overhead lockers, although it's too big to go under the seat. The external size is 32 x 19 x 45cm (12.6 x 7.5 x 17.7 inches), and the shoulder straps can be tucked away under the external back padding, safely out of reach of the carnivorous jaws of airport baggage conveyors. It has a large padded handle on the top for carrying the bag when the straps are stowed.
The bag itself is quite light, weighing only 1.7Kgs (3.7lbs), but if you're lugging around a particularly heavy collection of gear, the back of the bag has a loop to accommodate Kata's optional folding trolley system. There is another version of the same bag design, the 3N1-33, which is almost identical but also has a large well-padded compartment for a laptop computer. The external size is 7.5cm thicker, and the extra compartment has an internal size of 27 x 4 x 42cm (10.6 x 1.6 x 16.6 inches), easily big enough for a 17-inch laptop.