ULA Catalyst Review (75 L Backpack)

A lightweight and exceptionally tough pack with a seriously impressive carrying capacity.

ULA Catalyst Backpack
Catalyst Bag Front
Catalyst Backpack Straps
ULA Catalyst Waist Belt
ULA Catalyst Pack Side View
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ULA Catalyst Backpack
Catalyst Bag Front
Catalyst Backpack Straps
ULA Catalyst Waist Belt
ULA Catalyst Pack Side View
ULA Catalyst Backpack
Catalyst Bag Front
Catalyst Backpack Straps
ULA Catalyst Waist Belt
ULA Catalyst Pack Side View
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  • The ULA Catalyst is the company’s largest-volume ultralight backpack. With a capacity of more than 75 liters distributed between its main compartment and external pockets, the Catalyst is perfect for extended trips and thru-hikes.
  • With a customizable main compartment, expandable rear mesh porch, durable side pockets, and spacious hip pockets, ULA’s Catalyst offers the perfect blend of high-capacity, weather-proof storage, and easy access.
  • The Catalyst can be customized in a variety of ways, allowing any hiker to get a customized pack that perfectly fits their body size and shape.
  • With a foam-padded back panel and spacer mesh lining the shoulder straps and hip belt, ULA has taken all measures to make the Catalyst a very comfortable pack.
  • Keep in mind that you’ll probably find this pack too big for casual hikes. For trips that will last 5 days or less, a smaller pack will be more practical.

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ULA Equipment
Full suspension internal framed backpack
Camping, hiking, thru-hiking, travel

Pack Details

48 ounces
40 lbs
75 L
Black, Blue Blaze, Original Green, Grey, Multicam Camo, Orange, Purple, Red, Teal, Custom

Video Overview

Click Here to Learn More about ULA’s Catalyst Backpack

Written Review

One of the biggest challenges of doing longer thru-hikes lasting for several weeks or more is the overwhelming amount of gear and supplies that you need to bring along. Considering the weight and volume that you’ll need to carry, it requires a pack that’s both durable and lightweight. Another factor that hikers often overlook is comfort: if you will spend more than a week carrying a pack, you better make sure that it’s going to be comfortable. For a pack that excels in all these departments, you need to look no further than the Catalyst from Ultralight Adventure Equipment (ULA).

The Catalyst has the largest volume in ULA’s popular line of ultralight backpacks. It weighs in at approximately 48 ounces and has a total carrying capacity of 75 liters distributed between its several compartments. Available in a large number of colorways, the Catalyst is constructed from water-resistant and highly durable ULA 210 Robin Fabric. The Catalyst is rated to carry about 40 pounds of weight.

This is the perfect pack for extended hiking trips and thru-hiking, or for hikers who like to carry items beyond just the necessities such as photography or other technical equipment. ULA has more than 15 years of experience in crafting lightweight backpacking equipment and is one of the few remaining backpack companies with a US-based manufacturing facility.

A strong selling point of the ULA backpack lineup is the level of customization offered. With four options for torso size, five options for hip belt length, and your choice of J-curve or S-curve shoulder straps, you can be confident that the ULA pack you order will fit your body comfortably. In fact, ULA is one of the few manufacturers of hiking backpacks that provide sizing options especially made for female hikers.

The large main compartment of the Catalyst can hold up to 42.6 L. Instead of a porch or lid, it has a long extension collar with a roll top closure. This saves on weight while giving the Catalyst some flexibility in terms of volume and an extra degree of weather protection. The main compartment of the Catalyst has several interior pockets for organized storage of small personal items or for the storing of a hydration reservoir which can be fed through either of the pack’s two side hydration ports. If you need the additional space, the interior pockets can also be removed via the plastic clips that attach them to the main compartment.

The contents of the main compartment can be compressed using the single pair of side compression straps and the webbing strap above the roll top enclosure. This helps keep the load of the main compartment close to your body. The bottom of the Catalyst’s main compartment is also slightly curved, which tends to shift the heaviest load a little closer to your core. These are nice, well-thought-out features that make it easier to carry heavy loads.

Like any traditional pack, the Catalyst has a full-length rear mesh pocket that is ideal for storing wet items, raingear, or big pieces of equipment that you need to access quickly. This mesh porch has a huge capacity of 9.8 L, but the set of shock cords help keep everything organized and secured to the pack. It’s made of very fine, heavy-duty mesh material that helps to keep it from getting snagged and torn by loose branches.

In contrast, the side pockets are made of solid material, giving them much better protection against tearing and abrasion. Each pocket is large enough to hold two 1-liter water bottles and is strategically placed to be easily reached. The bottoms of the side pockets are reinforced with the same water-resistant material as the rest of the pack. To help secure the items, each side pocket features an elastic cord that is easily cinched closed.

The hip belt is much wider than usual packs, serving two important functions: it helps to transfer much of the load to the hip and also provides a lot of added storage space. The two large pockets on the hip belt are big enough to store a camera, a hat, gloves or snacks. They are closed by durable zippers and are hard-faced to prevent tearing. The hip belt snaps close using a traditional buckle which many users have reported to occasionally open – perhaps something that ULA needs to improve on.

In addition to being able to specify your hip belt length when you order the Catalyst, the height of the hip belt can also be adjusted using an easily detached Velcro connection in the rear part of the frame.

The shoulder straps also offer some quick-access storage for accessories with its multiple daisy chains and plastic D-rings. These are ideal for clipping small but essential items such as GPS units, cameras, or trekking gloves. The front load lifters that slide down the shoulder straps help bring the load of the pack closer to your shoulders, periodically relieving the load off your back.

The frame of the Catalyst is supported by two aluminum stays that come pre-contoured but can be removed and re-bent if needed. The stays sit right beside an interior foam panel that acts as a cushion between the main compartment and your back. The back foam panel and a lumbar pad made from the same material help to keep the Catalyst comfortable — quite an essential factor anytime you’re carrying a heavy load.

The back panel, as well as the hip belts and shoulder straps, are lined with a padded spacer mesh that increases comfort and provides some ventilation. However, we find that this design still does not provide enough ventilation for the back, resulting in the lower back getting hot pretty quickly. The holes in the spacer mesh also tend to collect debris such as small rocks and leaves.


ULA offers free repair or replacement to the original owner in event of product failure due to defects in material and workmanship. This warranty does not cover damage due to normal wear and tear, accidents, neglect, or improper use. Returned packs that are covered by the warranty must be recently cleaned in order for ULA to accept them. The Catalyst pack can be washed in a standard top-load or non-agitator type washer.


  • The Catalyst is the largest ultralight backpack from ULA and is perfect for long thru-hikes and for hikers who need to carry more than just the necessities.
  • Like ULA’s other packs, the Catalyst has a wide range of customization options. With the ability to choose between different shoulder strap shapes, torso sizes, and hip belt lengths, you can be sure that your customized Catalyst will fit like a glove.
  • Several load-shifting straps and shock cords allow you to shift the load of the pack to its most comfortable position. Foam-padded shoulder straps, hip belts, and back panel help enhance the comfort level of the Catalyst.


  • The Catalyst may be excessively large for more casual hikes. It’s generally recommended for trips that last longer than 5 days. For shorter hikes, a smaller (and cheaper) pack may be more practical.
  • The buckle of the hip belt seems to detach frequently, especially when carrying heavy loads. We are expecting ULA to improve the design of this buckle.
  • Although the back panel is padded with a space mesh, we find that it still does not provide enough ventilation when the pack is nearly loaded to full capacity. Perhaps a thicker spacer mesh can compensate for the compression due to an increased load.

 Final Thoughts

The Catalyst is one of the biggest ultralight backpacks available today. With its massive capacity, this pack is generally recommended for more experienced backpackers or those with special high-capacity requirements. As such, it’s not an all-around pack and not recommended for trips that will only last 5 days or less. For more casual hikers, we recommend checking out the 68-liter ULA Circuit.

As with all other ULA packs, we love how many customization options are available for the Catalyst. This ensures that you’ll always end up with a great fit, regardless of the size and shape of the hiker. The Catalyst is a highly functional pack that deliberately avoids unnecessary features and with its proven durability, it’s an ideal high-volume pack for your toughest and longest hikes.

Click Here to Buy ULA’s Catalyst Pack


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