auspex in the field auspex
Photo 1: Mountainsmith Auspex

The Mountainsmith Auspex is a top-loading internal framed pack offering extensive options and exceptional load carrying capability at a lighter weight than many of its competitors. While there are many packs that weigh less than the 4.1 pound (1.85 kg) Auspex, you will be hard-pressed to find one with as many features – convertible top lid, tough abrasion-resistant fabrics, an innovative bungee system, hydration system capability, water-resistant zippers, side panel access, and the ability to carry 65 pounds (30 kg). If you are a 20 pound (9 kg)-carrying fastpacker, the Auspex will be way more than you need or want. The Auspex is a light expedition worthy pack that is also ideal for climbing or mountaineering.


• Backpack Style

Internal frame, top-loading with side panel zipper access.

• Fabric Description

Pack body constructed of Dimension Polyant x-Pac VX-21 and VX-42 fabrics that utilize a 3-ply design with a grid of high tenacity fibers in the middle (somewhat like Spectra). High tenacity nylon is used for the bottom and other high wear areas. Breathable Brock foam and nylon mesh are used at contact points for moisture transport.

• Sizes (Size LT tested)

Sizes Torso Length (in) Torso Length (cm)
LT 19-22 48-56
MT 17-19.5 43-50
Chimera (Women) 15-17 38-43

• Volume (Size LT tested)

Sizes Volume (ci) Volume (L)
LT 4,000 66
MT 3,850 63
Chimera (Women) 3,600 59

• Weight (Size LT tested)

Sizes Backpacking Light Measured oz/yd2 (kg) Manufacturer Specification oz/yd2 (kg)
LT 65.3 (1.85) 64 (1.81)
MT Not measured 63 (1.79)
Chimera (Women) Not measured 58 (1.64)

• Volume to Weight Ratio

61 ci/oz/yd2, size LT (based on 4,000 ci and Backpacking Light measured weight of 65.3 oz/yd2)

• Load Carrying Capacity

60-65 lbs (27-30 kg) as estimated by Backpacking Light.

• Carry Load to Pack Weight Performance Ratio

16 (based on 65 lbs and Backpacking Light measured weight of 65.3 oz/yd2)



• Manufacturer’s Contact Information

(800) 551-5889


Ratings follow on a scale of 1 to 5, with 5 being the best, and are relative to other Backpacking Light tested framed packs.

Frame and Suspension – 4.5

pack frame suspension system

Photo 2 (left): The Auspex makes minimal contact with the user’s back creating greater airflow along the back panel. The exposed frame stays need to be adjusted for each user and can take some getting used to.

Photo 3: The waist belt of the size LT Auspex is supportive but large for a 34 inch (86 cm) waist.

The Auspex pack utilizes Mountainsmith’s Mountainlight suspension system. This system consists of two corrugated aluminum stays, a plastic mid-panel framesheet, padded shoulder straps, and a wide padded hipbelt. The stays are exposed in the lower section of the pack, and the hipbelt and upper shoulder pads are the only body contact points (Photo 2). The back panel is much more airy than a traditional full-contact design. Brock foam and nylon mesh, used for the shoulder and hipbelt padding, transports moisture and keeps the pack dry against your skin, even when worn without a shirt.

Side compression straps and a back bungee work together to keep loads compact. With the Auspex properly loaded and compressed, the load lifter straps and hipbelt stabilizers pull the pack close to your back for optimal pack stability and balance when hiking or scrambling on rough terrain. Torso length can be adjusted by moving the shoulder straps up or down along the two exposed corrugated stays. The sternum strap adjusts vertically along a unique piping channel, which offers no technical advantage but looks great. Stays are removable, but it is not an easy task. The user will most likely remove them once for bending and then leave them in the Auspex. It is essential to properly adjust the exposed stays to your back; one reviewer felt the non-adjusted stays jam into his back (Photo 2) on an extended hike. Another repeatedly hit his elbow when donning the pack at first, but then adjusted to the design.

Usable Features and Ease of Use – 4.5

fanny pack
Photo 4: The Auspex’s top lid converts into a very functional fanny pack without the need to remove the hip belt.

The Auspex is full of many usable features often found in much heavier packs. It has a floating top lid with two pockets. The top pocket has a water-resistant zipper and is accessible while wearing the pack. Another pocket, hidden underneath the top hood, is constructed of mesh for easy viewing of the contents and includes an internal key clip. The top lid converts to a convenient fanny pack for day tripping (Photo 4).

Convenient side pockets hold items such as a wind shirt or water bottle securely and are protected by high-tenacity nylon on the bottom for durability. The side pockets are easily accessible while wearing the pack. The Auspex is hydration system-friendly with a removable internal hydration sleeve and shingled exit ports on each side of the pack body. Elastic loops integrated into the shoulder straps keep hydration hoses secured and within easy reach. A water-resistant panel loading side zipper allows access to items inside the main body of the pack; however, our reviewers found it easier to access items through the top as the water-resistant coating makes the zipper stiff. The Auspex includes two ice-axe loops at the bottom of the pack’s back.

Although these features make the Auspex usable over a wider range of backcountry adventures, the added features increase the pack’s weight. The typical lightweight backpacker will find these features get in the way more often than they are needed.

The shock cord on the back of the pack is quickly removable from the side attachments making it easy to attach large objects, such as sleeping pads or tents, without the need to feed the items through a web of cords (Photo 5). Simply remove the cord attachments from one side, center the object on the pack, reattach the cords, tighten the one-handed cord lock, and the hiker is ready to go.

bungee cords bungee cords

Photo 5: The bungee system is very easy to use – just undo the cords, add your item, reattach, and cinch!

Load Volume Flexibility (Compression) – 4.0

The Auspex’s effective compression system allows it to comfortably carry loads much smaller than the maximum capacity. By tightening the side compression straps, tightening the bungee system, and leaving the top lid empty, the user can comfortably carry even day-sized loads with great stability. Because the aluminum stays are difficult to remove, the Auspex remains tall and stiff while carrying these minimal loads. With large volume loads, the exterior side pockets, top lid pocket, and shock cords across the back provide suitable expansion of an already large (by lightweight standards) pack.

Field Performance

Pack Load Carrying – 5.0

The Auspex can haul heavy loads with ease. During one field session on the badly washed out Enchanted Valley trail in Olympic National Park, a reviewer carried both his and his wife’s loads (approximately 35 lbs, 16 kg) in complete comfort. In an effort to find the pack’s carrying limit, the pack was filled with 50 pounds (23 kg) of water and rocks . Even with the rough terrain, the Auspex did not flex and carried the weight comfortably. In further tests, the pack was filled with 65 pounds (30 kg) of water and weights and taken for several miles on local trails. The Auspex carried this load comfortably. We think it could probably carry even more. Through the full range of loads carried, the wide hip belt and high-density foam shoulder straps transferred the weight as comfortably as packs weighing much more. The Auspex is a true expedition worthy load hauler. In addition, its compression system and slim pack design kept the load close to the user’s back for a good center of gravity.

Durability – 5.0

After extensive use, Mountainsmith’s Auspex only showed slight fraying in the piping that frames the base of the pack. All straps are internally sewn into piping which is very strong. The use of highly abrasion-resistant Dimension Polyant x-Pac fabrics enables the Mountainsmith pack to hold up well, even in off-trail hiking and climbing. Heavier high-tenacity nylon is used on the bottom of the pack for further durability in this high wear area.

The reinforced x-Pac fabric used behind the bungee made it possible to carry crampons without a reinforced bag. This narrow, durable pack makes an excellent companion for climbing trips.

Value – 4.0

At $230, the Auspex is not an inexpensive pack. However, you are getting all the bells and whistles such as waterproof zippers, convertible top lid/fanny pack, bungee system, durability, side access, high tech fabrics, and a suspension system that can handle expedition weight loads. Further, this is accomplished at just a hair over 4 pounds (1.85 kg). As a lightweight expedition pack, the Auspex is an excellent value.

Recommendations for Improvement

Mountainsmith has hit their target market quite well with the Auspex pack. While not as light as some other packs, you would have to eliminate features and durability to bring the weight down; this is simply not Mountainsmith’s goal with this pack. Our only concern with the Auspex is the exposed frame stays. During testing, we repeatedly scraped our triceps against the sharp stay edges, especially when the pack was filled to capacity. A better design would have the stays covered in soft fabric or at least sanded smooth along the edges.