Well, cordura, but yeah - I can testify to the durability of Tom Bihn bags, I've carried a Tom Bihn Café bag internationally for about 7-8 years and the only thing that's bust is the buckle which I can live without. It holds lots of tech stuff and could easily contain an EDC if I wanted to pass through TSA with all that. I've seen the Synapse backpack and I think it could pass as either a genteel briefcase or as a daypack provided you choose a neutral (blackish) color. I typically empty out my café bag when I go walkabout overseas, and fill it with stuff I find. Tom Bihn is the bomb.

Disclaimer: No consideration from Tom Bihn, just a happy customer etc.