Waterproof to shield your work clothes and laptop from puddles. The rolltop design is sleek and easy to close, and the cleverly designed rack hardware flips around so you can wear it as a messenger bag off the bike. A sheer back pocket lets your blinkie light shine from a secure location where it can’t rattle off on bumpy sideroads. Made of nylon in a waterproof rolltop design (made to be rolled down 3-4 times). Secure attachment system works on pretty much any bike rack,