The Zpacks Multi-Pack is a unique product that doesn't have any direct competition. Thanks to all of the available mounting options, you can use the Multi-Pack as a chest pocket hung from your pack's shoulder straps, a pack lid, a waist pack (fanny pack?), or even a shoulder bag (purse or man bag). The Multi-Pack has three buckles and one webbing loop on each side that can be used with the four pieces of webbing also included. All four pieces of webbing can be attached to a backpack on one end and to the Multi-Pack on the other, and the two larger pieces can also be clipped to one another to form a waist belt or shoulder strap when using the Multi-Pack alone.
The Multi-Pack as viewed from the front and back showing the variety of mounting options
The Multi-Pack is a good size for general all-around use with a volume of around 215 cu in (3.5 L). Zpacks uses a waterproof hybrid material composed of Cuben Fiber and Nylon for the Multi-Pack (this is the same fabric used on their Exo backpack). The Multi-Pack features a water-resistant zipper for access, and the water-resistance of the pack itself is enhanced by placing the zipper across the front of the pack rather than on the top. However, the Multi-Pack is not seam sealed. So while it is quite water-resistant, it will not survive submersion, and when used in a long downpour water will eventually leak in.
The Multi-Pack uses a water-resistant zipper mounted across the front, rather than on top
Thanks to the variety of mounting options, the Multi-Pack can be attached to most any backpack. I primarily use the Hyperlite Mountain Gear Porter or a GoLite Rush 20 for my trips and had no problems mounting the Multi-Pack to either. On a recent overnight trip I was able to load all of my gear into the Rush 20 with the Multi-Pack mounted as a front or chest pouch. Using the Multi-Pack in this configuration allowed me to shift some weight to my chest and provided me with quick access to my camera, a Sony Nex-5n, and my day's rations.
The Multi-Pack mounted to a GoLite Rush 20 for use as a front (or chest) pack
Overall, I believe the Multi-Pack is an excellent product that doesn't really have any direct competition. With the variety of configurations and mounting options, this is an item that easily goes from backcountry to front country. The only thing preventing a Highly Recommended rating is that while the Multi-Pack is really good at several things, it doesn't necessarily excel at any of them.