From Packhacker:

“The GORUCK GR2 is one of the most durable packs out there with tons of high quality material—1000D CORDURA®, YKK zippers, designed by an ex-green-beret—the thing isn’t gonna break. How do we know that? We’ve tested it on the road, everyday for a year. The founder of GORUCK, Jason McCarthy, states that he won’t use anything else but YKK zippers—and he built a company around putting heavy-ass weights in his bags to exercise with. If YKK zippers are good enough to hold up in combat, they’re good enough for one bag urban travel as far as we’re concerned. With all that durability, there is a weight penalty though. The GR2 comes in at 4.75 pounds when empty.”

Read more here.