Will it take a bear canister?

Yes — 53 L is enough for a standard canister plus multi-day food, which is exactly the trip profile this pack targets. That's a real advantage over the 37-45 L cottage packs it competes with on weight.

Carbon stays sound fragile — are they?

In normal use, no — carbon is stiffer per gram than aluminum, which is how the pack transfers load well at 28.6 oz. The honest caveat: badly overloaded or abused carbon can snap where aluminum would bend, so respect the pack's ultralight intent.

How does buying direct compare to cottage brands?

Outdoor Vitals ships from stock, so you skip the weeks-long made-to-order queues at Bonfus or Nashville Pack, and the direct model is why comparable Ultra-fabric packs cost more. The trade-off is a shorter track record than the established cottage names.

Do I need rain protection with UltraWeave?

The fabric itself is waterproof, so the usual setup is a light liner for seam insurance rather than a rain cover. Like all Ultra laminates it's tough to repair in the field, so repair tape matters more than a cover does.

What if the fit is off? There's no torso adjustment.

Correct — you choose a size at purchase and live with it, and there's essentially no retail presence for trying one on. Measure your torso twice against their chart, and check Outdoor Vitals' return terms before ordering if you're between sizes.

Ultralight Pack

~$330

Outdoor Vitals

Outdoor Vitals CS40 Ultra

Name: Outdoor Vitals CS40 Ultra
Brand: Outdoor Vitals
Price: 330 USD
Availability: InStock

The CS40 Ultra pairs Challenge UltraWeave 200 with carbon fibre stays for 28.6 oz at 53 L. Outdoor Vitals sells direct, which is why the price sits below comparable cottage packs using the same fabric.

Approx. price

~$330

Capacity

53 L

Weight

1.79 lbs

Best For

Thru-hikers wanting an Ultra-fabric framed pack without cottage-brand lead times

Buy from Outdoor Vitals →

Price and availability on Outdoor Vitals’s site may differ.

Specifications

What do these specs mean? →

Type

Ultralight Pack

Frame Type

Internal Frame

Capacity

53 L

Weight

1.79 lbs

Max Recommended Load

Not specified by the manufacturer

Torso Fit

See manufacturer sizing

Material

Challenge UltraWeave 200

Back Panel

Carbon fibre stays with EVA foam pad

Warranty

Manufacturer warranty; terms not published

Raincover Included

Fits BV500 Bear Canister

Features

Hipbelt Pockets

Pros

✓Carbon fibre stays are stiffer per gram than aluminium, giving good load transfer at low weight.
✓Challenge UltraWeave 200 is waterproof and highly tear-resistant.
✓$330 undercuts the Bonfus Framus and Zpacks Arc Haul Ultra using comparable fabric.
✓53 L is enough for a bear canister and multi-day food.
✓Direct-to-consumer sales mean shorter lead times than most cottage brands.
✓28.6 oz is competitive with framed packs 5 L smaller.
✓EVA foam pad backs the stays for comfort under load.
✓Hipbelt pockets included.

Cons

✗No published maximum load figure.
✗Carbon stays can snap rather than bend if badly overloaded, unlike aluminium.
✗UltraWeave is hard to field-repair.
✗$330 is still a lot next to the Durston Kakwa 55 at $279.
✗No adjustable torso.
✗Outdoor Vitals has a shorter track record than the established cottage names.
✗Warranty terms are not published the way major brands publish them.
✗Limited retail presence for in-person fitting.

Common Questions

Compare the Outdoor Vitals CS40 Ultra

vs Osprey Exos Pro 55 vs Outdoor Vitals Shadowlight Carbon 60

Related backpacks

Outdoor Vitals Shadowlight Carbon 60

The Shadowlight Carbon 60 pairs carbon stays with conventional woven fabrics rather than Ultra laminate, which is why it undercuts the CS40 Ultra by $40 while offering 7 L more. It is the largest carbon-framed pack in this catalog.

60 L1.97 lbs100D Robic nylon with 200D Spectra ripstop

Weight

1.97 lbs

Capacity

60 L

Frame

Internal Frame

Best for: Multi-day and thru-hike trips needing 60 L with a stiff, light frame

View details Outdoor Vitals

~$330

Ultralight Pack

Osprey

Osprey Exos Pro 55

4.1(37)

The Exos Pro is Osprey's answer to the cottage ultralight brands: 33.2 oz for 55 L, or 30.4 oz with the lid removed. It uses NanoFly, a 100D nylon crossed with 200D UHMWPE, over a 3.5 mm LightWire frame, and saves nearly a full pound against the standard Exos 58 at the cost of load rating and a fixed hipbelt.

55 L2.08 lbsRemovable LidVentilated back

Weight

2.08 lbs

Capacity

55 L

Frame

Internal Frame

Best for: Thru-hikers with sub-30 lb loads who still want a suspended-mesh frame

View details Check price

~$315

Ultralight Pack

Gossamer Gear

Gossamer Gear Mariposa 60

The Mariposa 60 is Gossamer Gear's signature pack, famous for its asymmetric pocket layout — one giant over-the-shoulder pocket that holds a tent, plus six more — and a removable back pad that doubles as a camp sit pad. It's the organized person's ultralight.

60 L7 Pockets2.16 lbs

Weight

2.14 lbs

Capacity

60 L

Frame

Internal Frame

Best for: Hikers who want everything reachable without opening the main bag

View details Gossamer Gear

🎒

~$350

Ultralight Pack

Nashville Pack

Nashville Pack The Cutaway

The Cutaway is Nashville Pack's frameless 40 L, built around a cutaway front panel that lets the mesh pocket expand rather than being pinched by the pack body. At 22 oz it sits between the Pa'lante V2 and the framed cottage packs.

40 L1.38 lbs210D Venom Gridstop ECO

Weight

1.38 lbs

Capacity

40 L

Frame

Frameless

Best for: Thru-hikers with low base weights who want more volume than a 37 L frameless pack

View details Nashville Pack

~$350

Ultralight Pack

Hyperlite Mountain Gear

Hyperlite Mountain Gear Contour 35

The Contour 35 is Hyperlite's frameless fast-and-light pack, and at 15.9 oz it is the only sub-pound pack in this catalog outside the Cotopaxi Batac. Dyneema Composite Fabric makes it effectively waterproof at a weight woven fabrics cannot reach.

35 L0.99 lbsDCF with Dyneema Gridstop and stretch mesh

Weight

0.99 lbs

Capacity

35 L

Frame

Frameless

Best for: Fastpacking and low-base-weight trips where every ounce is counted

View details Hyperlite Mountain Gear

~$350

Ultralight Pack

Six Moon Designs

Six Moon Designs Swift X

4.7(42)

The Swift X is the X-Pac version of Six Moon Designs' Swift, using the same Delrin hoop frame as the Swift V but in a waterproof laminate. At 38.8 oz it is heavier than most packs in this segment, which is the cost of the hoop and the fabric.

50 L2.43 lbsX-Pac laminate with Ultra Stretch pockets

Weight

2.43 lbs

Capacity

50 L

Frame

Internal Frame

Best for: Hikers wanting a flexible hoop frame in a waterproof laminate

View details Six Moon Designs

← Back to All Backpacks