Waterproof inner lining and zippers, Outer material is heavy duty canvas, Side pocket is large enough to fit most water bottles and drink containers. Pannier bag attaches securely to the elby rack. Inner top pocket large enough to fit an extra pair of shoes while keeping it separate. Internal sleeve fits most tablets and laptops. Top strap allows bag to be carried as briefcase while single adjustable strap allows the bag to be used as a cross body sling bag. Body strap attaches securely to the bag to ensure it does not get caught in the spokes.