Zpacks is a separate company from ULA Equipment; this page covers its Arc Blast as an ultralight alternative worth comparing with ULA's packs. The Zpacks Arc Blast is an ultralight backpacking pack built primarily from Dyneema Composite Fabric (DCF) around Zpacks' signature curved Arc frame, designed to minimize pack weight while still giving structure to a loaded multi-day kit. It's one of Zpacks' most recognized models among thru-hikers chasing a low base weight without going fully frameless.
Zpacks built its reputation as an early adopter of DCF — a waterproof, non-stretch laminate fabric originally developed for sailcloth — in backpacks, tents, and rain gear, at a time when most pack makers still relied on woven nylon exclusively.
Like ULA, Zpacks builds most packs to order rather than shipping from large retail inventory, and it offers separate hip belt sizing along with a range of color options — the two brands arrived at a similar direct-to-consumer, semi-custom sales model independently of one another, even though their suspension and fabric choices differ sharply.
What makes the Arc suspension different?
The Arc suspension uses a curved frame member that bows away from the wearer's back instead of running flat against it like a standard aluminum stay. That curve creates a gap between the pack body and the hiker's back, improving airflow while the frame's flex absorbs some of the bounce from uneven trail movement.
This is a structurally different approach than ULA's flat single-stay suspension: where ULA's stay is contoured to sit close against the back for a snug, stable carry, Zpacks' Arc is intentionally bowed to trade a small amount of stability for ventilation and a springy, load-absorbing feel.
What's the Arc Blast's fabric like?
The Arc Blast's body is built mainly from Dyneema Composite Fabric, a laminated, non-woven material valued for its strength-to-weight ratio and complete resistance to water absorption, unlike woven nylon which soaks up water weight in wet conditions. DCF doesn't stretch the way nylon does, so a DCF pack tends to hold its shape under load rather than sagging over time.
The trade-off is abrasion resistance: DCF handles tension well but can be more prone to puncture or abrasion damage in high-friction spots than a heavier woven nylon, which is why some DCF packs pair it with reinforced panels or nylon in the highest-wear areas.
How does the Arc Blast compare to the Arc Haul?
The Arc Blast and Arc Haul share the same curved Arc frame but differ in body construction and closure style: the Arc Haul is made from Gridstop fabric with HDPE grid threads rather than DCF, and Zpacks says it handles loads up to around 40 lb, while the Arc Blast leans toward a more minimalist, lighter build.
Hikers choosing between them are typically weighing the same trade-off that shows up across the ultralight category: slightly more weight and durability with the Arc Haul, versus a slightly lighter and more minimalist carry with the Arc Blast.
Who should consider the Arc Blast?
The Arc Blast suits experienced ultralight hikers who've already dialed in a low base weight and want a pack that won't add unnecessary ounces, since DCF construction and the Arc frame reward disciplined, minimal packing more than a forgiving, overstuffed carry. It's less suited to hikers still accumulating gear or expecting to load a pack past its intended range regularly.
Hikers newer to backpacking, or those who tend to carry bulkier gear, often find a more structured, moderate-weight framed pack — like ULA's Circuit — a more forgiving starting point before moving toward a minimalist DCF build like the Arc Blast.
Climate and terrain matter too: hikers spending long stretches in brushy, high-abrasion terrain may find a heavier woven-nylon pack more forgiving day to day, while hikers on established, well-maintained trails are less likely to stress-test the Arc Blast's DCF panels against branches and rock scrambles.