Straps down both flanks pull the whole bag in, or let it out — the Expandable Travel Techwear Backpack changes size with the trip rather than with the packing. Built in Oxford fabric, in three colourways. Good to know Which colours can I get? Khaki, blue and black. How does it expand? Compression straps on both sides release to open the body out. What is it made of? Oxford fabric. More in our techwear backpacks, or browse the rest of our techwear bags.