Ripstop
A fabric with thicker threads woven into it in a grid. If the pack tears, the grid stops the rip from spreading. It works against branches, rocks and airport conveyor belts alike.

Denier (D)
A unit that indicates the thickness of the fibre. The higher the number, the greater the durability – and the weight. 200–300D is fine for the city. 400–600D can take some punishment.

DWR finish
A treatment that repels water. Droplets roll off the fabric instead of soaking in. It wears off over time – but you can restore it with a reproofing spray.

Reinforced base
You throw your pack on wet ground, drag it over rocks, sit on it. The base has to be made of tougher fabric – higher denier, rubberised or Cordura.

Reliable zips
The zip is the weakest link. When it bursts in the rain on a ridge, the improvising begins. YKK zips are the benchmark of quality. They run smoothly, don't snag and don't split open.

Tough buckles
Duraflex or ITW Nexus. These are buckles that won't crack easily – not in the frost, not even if you accidentally step on them.
