The Ortlieb Office Bag QL3 is the latest incarnation of Ortlieb's waterproof briefcase pannier. What's changed from the QL2 bag is the attachment system: it's still quick-release but the hooks are recessed, so the briefcase looks more businesslike when you're off the bike. Or as Ortlieb put it: 'Flat mounting elements ensure smooth back side.' Yep.
A good set of panniers can be an investment that sets you up for many years of happy load hauling. Keep your eyes peeled and you'll see plenty of Ortlieb's Back Rollers on both commuters and grizzled tourists. There's a reason for their ubiquity - they're bloody good.
Ortlieb know a thing or two about making quality bike luggage and the Ultimate 5 Plus Bar Bag has been on their books for a while now, but it's starting to look a little expensive and basic.