The D66 includes one D28 and one D38 dry bag to create 66 liters of 100% waterproof storage. Modular packing has significant advantages over a single bag of the same volume. The two-bag D66 system makes packing and organizing your gear easier, allows for quicker access to your gear, and enables strategic separation of your gear; keeping your clean clothes separate from your wet tent. Each D-Series bag is also designed to mount directly to your bike, so you truly get three different bags in one. Use the D28 on local trails, strap on the D38 for around town, or connect the D66 for your longer adventures.