The Don Lid is a flat lid for the Alpine packs. Constructed out of waterproof Ultra or X-Pac fabrics. There is a #8 YKK waterproof zipper on the bottom side so it can still carry a small amount of gear. The flat profile increases headspace if you are wearing a helmet. with or without daisy chains.
there is no upcharge for this lid on pack order. Many buy this as a spare lid. weighs about 3 ounces.