X-Pac Circuit
$149.99 – $199.99




1. TORSO FIT
- Standing upright, tilt your chin to your chest.
- Locate your C7 Vertabra—the large lump at the base of your neck.
- With flexible tape, measure down the length and natural curvature of your spine to your iliac crest/ the top of your hipbone.
- This measurement in inches is your torso length.
TIP: If you're between 2 sizes, order the smaller size. Still not sure? Contact us.
2. TORSO CHART
We've found most people in these height ranges fall into these torso/pack sizes. That being said, it is always best to measure your torso using the guide above.
If you're between sizes and you are getting a FRAMED pack, we recommend you size DOWN!
If you're between sizes and you are getting a FRAMELESS pack, we recommend you size UP!
If you have questions, or your torso size doesn’t seem to make sense for your height, please contact us.
3. HIPBELT FIT
Use the following method to determine your hipbelt inches, then head to Step 4 to see the hipbelt size you need.
MEN
Pant Waist Size + 2".
WOMEN
CURVY HIPS: Smallest part of your waist + 5".
STRAIGHT HIPS: Smallest part of your waist + 3".
KIDS
Smallest Part of waist + 2".
4. HIPBELT SIZE CHART
Find the hipbelt measurement you calculated in Step 3 on the chart. That will be your hipbelt size.
TIP: If you are on the outer edge of a size, order the larger size. [ Ex: If you are 38", you will notice 38" is the last number of the Medium Hipbelt and the first number of the Large Hipbelt. You would want to order a Large.]
5. SHOULDER STRAPS
The downward slope of your shoulder profile usually determines strap preference. You can assess your shoulder slope profile by looking in a mirror or having a friend look at the angle of your shoulder from the base of your neck to your shoulder point.
If there is relatively little or no downward slope, you have what is referred to as flat or squared shoulders.
If there is a noticeable downward slope, you have what is referred to as standard or sloping shoulders.
J STRAPS
J-straps are the traditional straight straps. They are best suited for people with flat or square shoulders, as their flat shape provides better surface contact and less rub.
S STRAPS
S-straps contour body curves. They are best suited for people with standard or sloping shoulders, as their contoured shape better hugs your shoulder slope.
TIP: If you have a short torso but a larger upper body, you may need a slightly longer strap. If you are very large in the upper body, you might need XL shoulder straps. Contact us, and we would be happy to make these customizations so your pack is comfortable and fits well.
MADE IN THE U.S.A.
FREE U.S. DELIVERY
LIFETIME WARRANTY*
TUNE-UPS & REPAIRS*
DESCRIPTION
These limited run X-Pac Circuit backpacks are constructed of Dimensional Polyant X-Pac materials. We have specially chosen fabrics from VX-07 all the way to VX-51 to let you decide on how you want to balance durability and weight. We added snaps to the roll top to give you a little extra usable room, as well as making it easier to roll down. We made a limited number of each size and color so be sure to get one while you can! Note that to maximize water resistance of the X-Pac Circuit, these packs do not have bladder hose ports and also there is no ULA logo on the pack.
This is one tough pack that will give you years of hiking bliss, even if you are a bit tough on your gear. This pack will take the abuse of a 2,600 mile hike and beg for more.
AT A GLANCE
CIRCUIT [WEIGHT BY SIZE | OZ]

VOLUME: 4,200 CU IN | 68 L
MAX LOAD: 35 LBS | 16 KG
These limited run X-Pac Circuit backpacks are constructed of Dimensional Polyant X-Pac materials. We have specially chosen fabrics from VX-07 all the way to VX-51 to let you decide on how you want to balance durability and weight.
FEATURES
- X-Pac Materials
- YKK Water-Resistant Zippers on the Hip Belt Pockets
- Diamond Black Robic Shoulder Strap Accents
- Rolltop Closure with Snaps
- Internal Suspension Hoop
- Padded Backpanel
- Contoured Shoulder Straps
- Front Shock Cord
- Front Mesh Pocket
- Side/Top Compression Straps
- Trekking Pole Retention Loops
- Bear Canister Capable
- Single Aluminum Stay (2.0 oz)
- Sternum Strap
WEIGHT BY FABRIC
VX07, VX33 WEIGHT: 39 OZ | 1,106 GM
VX21, VX21RS WEIGHT: 41 OZ | 1,162 GM
RX40 WEIGHT 43 OZ | 1,219 GM
VX425 WEIGHT 45 OZ | 1,276 GM
X50, X51, X51RS WEIGHT 47 OZ | 1,332 GM
CAPACITY
REC. MAX LOAD: SUB 35 LBS
PACK VOLUME
TOTAL VOLUME: 4,200 CI | 68 L
BREAKDOWN:
- Main Body: 2,400 CI | 39.3 L
- Front Mesh Pocket: 400 CI | 6.6 L
- Left Side Pocket: 400 CI | 6.6 L
- Right Side Pocket: 400 CI | 6.6 L
- Extension Collar: 500 CI | 8.19 L
- Left Hipbelt Pocket: 91.5 CI | 1.5 L
- Right Hipbelt Pocket: 91.5 CI | 1.5 L

FAQ’S
Q: WHAT IS A SUSPENSION HOOP?
A: The suspension hoop used in the Circuit is our minimal solution to transferring load between shoulder and hip. If you imagine an upside ‘U’ you get a sense of how the hoop is positioned and how it functions. The upper arch of the ‘U’ ties into the shoulder straps, while each leg of the ‘U’ ties into the hipbelt. These points of contact allow for a range of suspension flexibility while being rigid enough to support loads up to 35 lbs. In addition, because the suspension is located on the periphery of the pack body, and the back-panel is stiffened slightly with dual density foam, the result is a pack that can handle the load but does not dictate your body’s movements — but rather responds to how you move. Personally, when the loads are kept below 35 lbs, we find this pack to be the most comfortable in the ULA line-up.
Q: CAN A BEAR CANISTER FIT IN THE CIRCUIT?
A: Every bear canister on the market will fit into the Circuit vertically. Unfortunately bear canisters will not fit in the Circuit horizontally. Keep in mind it is best to pack something between the hard sided canister and the bottom of the pack.
Q: WHERE DO I STRAP MY SLEEPING PAD?
A: If you are using an inflatable pad, we recommended storing it in the interior of the pack to avoid punctures. A foam pad can easily be secured beneath the top compression strap that goes over the top of the pack or beneath the front shock cord compression. Although not necessary for optimum performance, positioning your sleeping pad into the interior of the Circuit (against the back-panel) is also a good solution.
Alternately, you can build your own pack and add Bottom Straps, or a top Y-strap to carry your pad externally.
Q: CAN A WATER BOTTLE FIT IN THE SIDE POCKETS?
A: Each side pocket can accommodate two 1-Liter ‘Big Slam’ style bottles. A Nalgene-style bottle will also fit, but in your quest to lighten up, that should have been replaced a long time ago! In general most people can reach back and retrieve a bottle, drink, and return the bottle to the pocket without removing the pack. The top of the side pockets are angled for easier access.
Q: HOW DOES THE TOP OF THE PACK STAY CLOSED?
A: The top of the pack closes like a dry bag (also known as a rolltop) very similar to what river runners use to create a water resistant seal for their gear bags. The back of the collar is slightly taller than the front. Once you are packed, the collar can be rolled down upon itself to effectively create a barrier to water penetration. Once rolled, each side of the collar can be buckled to the sides of the pack or the two yellow buckles on the top can also be fastened to each other.
As for access, once the collar is rolled and fastened shut, you would need to unbuckle the compression straps and unroll the collar to access the inside of the pack. However, the roll-top only needs to be rolled shut when the weather dictates. If the sky is dry, the collar can simply be folded forward. Vertical compression can still be achieved by buckling the collar to the sides of the pack.
TECHNICAL FABRICS
X-PAC
…one of the most popular high-performance technical fabrics in the industry. Low stretch, abrasion resistant, and a high denier face fabric strike a near-perfect balance between weight and durability. These multi-layered laminated fabrics are waterproof to 200+ PSI.
RX40 ROBIC
X-Pac RX40 is a highly durable, abrasion-resistant technical fabric with a high tear strength. RX40™ is a laminate fabric comprised of the following layers: Triple Coated DWR Diamond Weave 400D Robic Nylon face, Black Polyester X-PLY at 22 degrees, 0.25 mil PET film, and a 50D Poly Taffeta backing.
STANDARD X-PAC VX07™
Standard X-Pac VX07™ Fabric uses heavy weather technology to achieve a great combination of light weight and good tear resistance. This laminate fabric is comprised of the following layers: C6 DWR 70 denier Polyester Face, Black Polyester X-Ply™ at 22°, 0.25 Mil PET Film, and a 50 Denier Polyester Backing.
X-PAC VX07RS™
X-Pac VX07RS™ s a lightweight, highly durable, abrasion-resistant technical fabric with a high tear strength, featuring a softer hand than the standard VX07 because it uses a waterproof coating instead of a film.
TERRAIN X-PAC VX21™
Terrain X-Pac VX21™ Fabric is one of the most popular high-performance technical fabrics in the industry. The combination of low stretch, waterproof construction, and 210 denier face fabric strikes a near-perfect balance between weight and durability.
HIGH VISIBILITY X-PAC VX25
High Visibility VX25 Fabric is made with UV resistant dyed polyester face fabric and was made to enhance safety. This laminate fabric is comprised of the following layers: C0 DWR 250 Denier Polyester Face, Black Polyester X-Ply™ at 22°, 0.25 Mil PET Film, and a 50 Denier Polyester Backing.
CAMOUFLAGE X-PAC X50™
The Camouflage X-Pac X50™ Fabric uses extra tough 500 Denier Cordura face fabric to create a highly abrasion resistant, tear resistant, high tensile and waterproof material that’s super bomber and can handle even the toughest of conditions. This laminate fabric is comprised of the following layers: C6 DWR 500 Denier Cordura Nylon Face, Black Polyester X-Ply™ at 22°, and a 0.5 Mil Shiny Polyester Film Backing.
X-PAC X51RS™
This X-Pac version is the same as the X51, with the addition of a ripstop weave to increase tear strength and stitch holding capabilities.
WHAT PEOPLE ARE SAYING…
1 review for X-Pac Circuit
GO GET IT.
MORE FROM THE ULA PACK LINE
ULTRALIGHT PACKS FOR EVERY ADVENTURE
You may also like…
-
Sale!
ULA Alpha Knife
Original price was: $129.99.$89.99Current price is: $89.99. -
Sale!
Replacement X-pac Hipbelts
Original price was: $59.99.$39.99Current price is: $39.99. -
Sale!
Cordura Spare Tire
Original price was: $49.99.$34.99Current price is: $34.99. -
Sale!
2023 Catalyst
Original price was: $299.99.$229.99Current price is: $229.99.
Oklahoma –
I purchased my X-PAC Circuit last winter when ULA had just put it on the market. There were some problems with the first several that were sold due to water leaks. Peter (Owner & Phone Representative) informed me of the problem and told me that ULA was working to fix the problem and offered to refund me my money. I was really impressed that he was so honest with me regarding his X-PAC’s nascent history. It’s rare that a business owner values doing the right thing over profit.
So, I waited a few months… it was cool because hiking season was a ways off. Peter and I checked in with each other monthly on pack development progress.
FFW to Spring – I took this beauty on a 600 mile trip on 2 Caminos through Spain & Portugal. The pack was most certainly water proof. Suspension, while not robust, was extremely comfortable. Can do 30 Lb but I prefer it in the mid 20’s or less. I’ve received many compliments and inquiries regarding this pack. I am very OCD with my backpacks and love my X-PAC so much I have contemplated buying another one, like I do trail runners that work for me (quality, material & specifications are mercurial!)
This is the second review I’ve ever written. I’m grateful to ULA for making me a made to order quality pack and having some class while doing it.
I have worked several seasons in the past as a backcountry mountaineering Park Ranger, thru hiked the PCT & AT, as well as the Colorado & Arizona trails. I write this in an attempt to lend credence to my testimony; however, there are a lot of quality shoes & backpacks out there & the best are the ones that fit YOU!
I promised Peter that if I was pleased with his product that I would leave a review. Promise kept.
Well done ULA