The ULA Ultra Circuit SV (48L) is an ultralight-style roll-top backpack made using an ultralight waterproof fabric called Ultra that’s significantly more abrasion-resistant than Dyneema DCF or the Robic Nylon used in other ultralight backpacks. The ULA Circuit SV (Small Volume) reviewed here is a lower volume version of the popular ULA Circuit (68L) backpack for hikers who don’t need to carry as much gear, water, or food. The only difference between the smaller ULA Ultra Circuit SV (48L) and the larger ULA Ultra Circuit (68L) is the volume of the main compartment.

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• Weight: 35.8 oz (size medium)
• Volume:  48 Liters, including the extension collar and external pockets
• Fabric: Ultra 200 and Ultra 400 in high-wear areas
• Mfg. Rec’d Max Load: 35 lbs
• Mfg. Rec’s Base Weight: 15 lbs
• Torso Lengths: 15-18″, 18-21″, 21-24″, 24″+
• Hip Belt Sizing: 26-30″, 30-34″, 34-38″, 38-40″, 42-47″, 47″+
• Seam-taped: No
• Hydration system compatibility: No
• Load lifters: Yes
• Bear canister compatibility: BV500 fits vertically, BV475 fits horizontally in the extension collar, BV450 and BV425 fit horizontally in the main compartment.
• Made in the USA
• Pros: Ultralight, waterproof fabric, excellent hipbelt, wide range of sizes, male and female models
• Cons: Not seam taped or seam-sealed, top Y-strap interferes with load lifters

ULA decided to create a smaller 48L volume version of the original 68L Circuit Backpack because backpacking gear has become noticeably more compressible and lighter weight in the past five years and there is less demand for high-volume backpacks like the original 68L Circuit.

The Circuit SV is available in 400D Robic Nylon or Ultra 200 and Ultra400. All of these materials are highly durable, although the Ultra Fabric is substantially more abrasion-resistant than Robic Nylon and waterproof.

Backpack Storage and Organization

The Ultra Circuit SV is organized like most ultralight backpacks with a mesh front pocket.

The ULA Ultra Circuit SV is laid out like a standard ultralight backpack with a front mesh pocket, side water bottle pockets made with solid fabric, and a single tier of side compression straps. It’s a roll-top pack (without any top snaps, a stiffener, or velcro at the top of the extension collar) that can be secured to the sides of the pack with straps and buckles or clipped together on top. If the latter, the extra side straps can be looped around the backpack to provide front compression or act as an attachment point to lash gear over the front mesh pocket. This can be handy for carrying snowshoes since they won’t fit under the side compression straps.

The side water bottle pockets are easy to reach while wearing the backpack, and you can get bottles in and out of the pockets. There is an elastic cord with a cord lock along the top of the pocket to secure tall skinny bottles, and while a 32 oz Nalgene bottle fits, the pockets aren’t deep enough to store it reliably: you’re better off using a taller skinny bottle. The pack’s shoulder straps run through holes in front of side pockets and are anchored inside. While this helps pull the pack closer to your hips, small items can fall out if placed inside the side pockets. 

Nalgene bottles have a tendency to pop out of the side pockets. You’re better off using tall skinny bottles.

The front mesh pocket, made with highly durable UltraStretch Mesh, is excellent for storing wet or loose layers you want easy access to without having to open up the roll top. The pack comes with an elastic cord that lays over the mesh and is good for attaching wet gear to the backpack’s outside, although I prefer to remove it so it doesn’t snag on protruding vegetation.

There are two zippered pockets on the exterior of the hip belt, large enough to store a point-and-shoot camera, snacks, bug dope, and such. The fronts of both pockets are hard-faced and have heavy-duty waterproof zippers. Hipbelt pockets are a place that often experiences high abrasion if you hike off-trail and where the Ultra fabric shines.

The hipbelt pockets are large and have waterproof zippers.

The inside of the pack bag is one big space without any hydration ports or a place to hang a hydration system, although there are two gear loops inside from which to hang a hydration pocket or a smaller accessory pocket (sold separately). While the entire pack can hold 48L, the main pack bag, including the extension collar, only has a volume of 37L of storage while the remainder is distributed in the open and hipbelt pockets.

The inside of the pack bag is also NOT seam-taped or seam-sealed, even though this is possible, and other pack manufacturers who use Ultra and Dyneema DCF do so. ULA says they don’t seam-tape because it would interfere with making pack repairs. I don’t understand why that would make a difference.

Regardless, I still recommend using a pack liner, even on packs that are seam-taped and made with waterproof fabric, because a liner has more uses beyond keeping the inside of your pack dry. (See: Do You need a Pack Liner for a Waterproof Backpack?)

The Ultra Circuit SV has two frame components: a Delrin (fiberglass) hoop that runs around the perimeter of the back panel and a central aluminum frame stay. The hoop doesn’t provide a structural function in terms of load transfer to the hip: its primary purpose is to prevent the pack from collapsing on itself when you pack it. The frame stay does the real load transfer work and helps prevent the pack bag from barrelling when the pack is full. It is pre-curved and helps drive the load into your lumbar region. Both the Delrin loop and the central frame stay components are not intended to be removable.

Backpack Frame and Suspension

In terms of load distribution, it’s best to place your heaviest items, such as food, closer to the center of your back or just above the hip belt. Weight placed higher up in this pack, with its single frame stay, tends to sway and can throw you off balance.

The back of the pack is made with thin foam covered with mesh fabric that keeps your torso comfortable even on hot and humid days. It’s not ventilated like a suspended mesh pack, so you’ll still sweat, but it’s also not smooth like a back panel made with nylon. It can, however, pick up forest debris, like pine or spruce needles, if you lay it down on the ground.

Like ULA’s other backpacks, the Ultra Circuit SV is available with traditional male (J-shaped) or female-friendly and unisex (S-shaped) shoulder straps, although many men prefer those S-shaped straps as well. I requested them on this pack to show you what they look like (above). The S-shape is suitable for people with sloping shoulders or well-developed chests and can help make the sternum strap (which slides up and down on a webbing strap) more comfortable. ULA packs are very popular with women backpackers for this reason.

The hipbelt has two adjustable levels and closes with a center buckle.

The hipbelt is equally impressive, if not more so. It has top and bottom webbing straps, so you can adjust the tension to match the curves of your hips while preserving the simplicity of a central buckle. I think the ULA Circuit SV backpack has the best hipbelt available today among ultralight pack makers in this weight class in terms of fit, comfort, and load transfer. It rides securely and comfortably over your iliac crest and won’t slip even if you have a heavily loaded pack.

The hipbelt is also replaceable and available in an impressive range of sizes, so you can dial in a good fit even if you’re on the ultra-slim or the oversized end of the spectrum. It attaches to the pack with a big block of velcro behind the padded back panel. That velcro block is taller than it has to be by about 2″, so if you need to, you can raise the hi belt up and shorten the torso length or vice versa. In other words, you get the convenience of an adjustable torso length without incurring the added weight and complexity that having one usually requires. This degree of adjustability has always been a feature of ULA’s larger backpacks that has set them apart from other fixed torso-length packs.

The pack has one compression strap on each side.

External Attachment Points/Compression

The Ultra Circuit SV has one tier of side compression straps located above each side pocket. In addition to helping compress puffy gear stored inside the pack, they can also be used to secure long skinny items to the side of the pack, like Tenkara fishing rods or a trekking umbrella. They have limited utility for winter hiking and backpacking; however, since they close with webbing strap adjusters, which freeze up in winter, and not side-release buckles.

A single top strap holds the top of the roll top down and works the best.

Like all ULA backpacks, the Ultra Circuit SV’s shoulder straps have plastic rings to hang gear like GPS receivers or a Garmin Inreach mini 2. The sternum strap slides up and down a piece of webbing sewn to the front of the shoulder straps and is easy to adjust.

The Circuit SV comes with a single top strap that runs from above the shoulders to a buckle in the front of the pack to hold down the rolltop and any items you might want to carry on top of the pack. A Y-strap is available as well, but I recommend against using it. The slack webbing in the Y-strap is very long and hangs down over your shoulders, not down the front of the pack, out of the way. This is ungainly and interferes with using the load lifters. It’s a very curious design, and I recommend rolling your own rather than using the ULA Y strap unless they change it.

The slack of the Y-strap hands down over your shoulders and chest and interferes with the load lifters.

There are additional gear loops at the base of the pack where you could also secure a tent and extra gear loops around the front mesh pocket. Again, the straps for these are sold separately. Finally, the Ultra Circuit SV includes a pair of elastic trekking pole/ice axe shaft holders at the top of the front mesh pocket. These are free.

Comparable Ultralight Framed Backpacks

Recommendation

The ULA Ultra Circuit SV Backpack is a 48L version of the popular ULA Ultra 68L Circuit Backpack and is designed for 3-5 day trips that don’t require carrying large amounts of gear, food, and water. While the two packs are virtually identical (except for the volume of the main compartment), I prefer the 48L version because it’s nimbler and more comfortable to carry than a higher-capacity backpack. (It’d be good if ULA would include the width and height dimensions of both packs on the products’ web store pages so you could compare them.)

The Ultra Circuit SV is made with Ultra 200 and Ultra 400, a pack material that’s more abrasion-resistant than Dyneema DCF or the 400D Robic Nylon used in the Robic Circuit or Robic Circuit SV backpacks, also sold by ULA. If you hike in mountainous terrain or off-trail, I’d recommend getting the Ultra version of the Circuit SV for the added abrasion resistance.

If you’re considering purchasing a ULA Circuit SV, the things that set it apart from other manufacturers’ backpacks are sizing and fit. If you require special sizing in height or girth or want S-shaped shoulder straps, the Circuit or any of ULA’s other higher-volume packs are hard to beat.

Disclosure: ULA donated a backpack for review.

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