Ripstop nylon

Ripstop nylon is a fabric woven with a reinforcing crosshatch pattern of thicker threads at regular intervals, visible as a faint grid if you look closely at the material. The reinforcing threads are there to stop a small puncture or tear from spreading further across the fabric, which is why the material is common in lightweight backpacks, packable jackets, and stuff sacks where durability has to be balanced against low weight.

For one-bag travel gear, ripstop fabrics let manufacturers use a thinner, lighter base material than they otherwise could, since the grid reinforcement compensates for some of the strength that thinner fabric would normally lack. This is part of why packable daypacks and ultralight rain jackets can be both very light and reasonably durable at the same time.

When comparing gear, a higher denier number generally means a thicker, more abrasion resistant ripstop fabric, at some cost in weight and packed size, while a lower denier packs smaller and lighter but is more prone to abrasion over time. A common misconception is that ripstop fabric is puncture proof, when it only limits how far a tear spreads once the fabric is already damaged, rather than preventing damage in the first place.