Classic randonneuring features meets the universal 137 Basket. This bag fits a 12-pack with room to spare. For a larger version, check out the Rack Bag.
The Wald 1372 provides a stable platform that traditional randonneuring racks just don't have. Its also inexpensive and can be mounted by itself or with any rack. The Basket Bag couples that with abundant pockets and weatherproof protection.
Two buckled straps secure the bottom, while the lid keeps everything down tight, but still accessible with one hand. The lid has an elastic cord running through it, with hooks like a bungee net!
Shoulder strap attachment points make this bag excellent off-bike as well. With the side inserts removed, the bag can cinch down into an elegant triangle, so you're not lugging around a bulky box.