Rab Protium 27 Daypack Review

Bottom Line

Rab’s brand-new Protium line debuted in Spring 2025, and the Protium 27 quickly climbed into the top half of our best daypacks for hiking list. Its impressive comfort, organization, user-friendliness, and durability immediately stood out during testing, earning it an Editor’s Pick Badge in the process.

Gear Analyst Ian Krammer accrued over 200 miles testing this pack in Utah’s slot canyons, Colorado’s snowy Rockies, and Denver’s rolling foothills. He liked its versatility but generally reserves the Protium 27 for long days, bigger gear carries, and shoulder seasons. With a large 27 liter capacity and technical features, this day pack is bulkier than what we recommend for shorter and casual hikes. The shoulder straps were very comfortable, but we found them a bit thin and weak for loads over 25 pounds. Plus, its higher price point may not work with everyone’s budget. Even so, the Protium 27 is worth every penny if you’re after a robust and versatile option for tackling tough conditions and extended treks.

Comfort

Our favorite thing about the Rab Protium 27 is the highly customizable fit.  Rab includes a huge hook-and-loop adjustable mesh backer that slides up or down to accommodate almost any torso size. Senior Gear Analyst Ian Krammer is 5’6 with a slender frame, and he was able to dial this pack in to suit his body shape in a matter of minutes. 

The mesh and foam molded back panel and shoulder straps rival the comfort of other premium packs from Osprey or Gregory that we’ve tested. On an 85°F day in Utah’s Dead Horse Point State Park, Ian’s back and shoulders stayed cool thanks to the Protium’s excellent airflow. The thick, cushioned foam waist panels and highly adjustable sternum strap made all-day wear effortless, even on demanding terrain. Despite its larger 27-liter size, the Protium 27 distributes weight evenly, offering day hikers a stable and strain-free carry. So far, our longest hiking day with this bag has been 22 miles in wet fall conditions – with no hot spots or complaints.

That said, we’ve had a few small issues with the Rab Protium 27. When minimally packed or empty, it rides high on our backs, which can cause the top of the Protium to press into the back of our necks. This issue goes away with more weight in the bag and can be mitigated by adjusting the back panel. However, this issue is unique to the Protium.

Ian liked the breathability of the shoulder straps, but they felt a bit thin and flimsy when carrying heavier gear. On a dawn-to-dusk winter trip to Rocky Mountain National Park – weighed down with everything from poles to gaiters to traction devices – his shoulders were a bit sore from the shoulder straps pulling on his frame. We’d like to see a bit more form and padding on these, more like the REI Trail 25 or the Gregory Zulu 30, which don’t have this issue. 

Still, these are minor problems – the Protium 27 is a comfortable all-around bag, and we reach for it time and again because it rides so well.

Organization

The Rab Protium 27 is an efficient backpack with all the storage we want on trail. The huge main compartment has plenty of room to handle bulky winter gear or shoulder-season essentials. But it’s slightly tapered at the bottom and has no dividers. That meant we needed to pack heavier items slightly higher, and it took careful packing to maintain balance. A stretchy mesh pocket on the outside is perfect for layers that we take off and on, such as  jackets or gloves. Inside, an internal mesh zippered pocket corrals small items, and a top-access zippered pocket with a key clip secures valuables like wallets and keys. Plus, Lash points and trekking pole attachments mean everything has a place

Whether you hike with a water reservoir or prefer water bottles in the side pockets, the Protium will work for you. The external hydration bladder pocket works with most big brand options, and the tube routing is simple since it comes right out of the top of the bag and down the shoulder straps. Deep side pockets with durable micromesh can accommodate narrow or oversized water bottles, with a set of compression straps to prevent bottles from shifting as you hike.

That said, the Protium 27 is the only daypack on our list with an external hydration reservoir pocket, located behind the back panel. We like this design because it simplifies tube routing, but the top opening is awkwardly tight, making it a struggle to slide in a full bladder. In fact, Ian found he had to underfill his 3 liter reservoir to get his Gregory bladder to fit inside. 

Despite these minor flaws, the Protium 27 remains a highly functional pack for hikers who value thoughtful storage and adaptability.

User-Friendliness

It’s rare that a new pack comes on the scene and immediately makes our best-of list, but the Rab Protium 27 is as user friendly as daypacks come. The pocket layout is intuitive, and four compression straps can cinch things down tightly.

Our only complaints about user friendliness come down to the slim water bladder pocket design and technical features. As mentioned above, the external hydration pocket design is a bit narrow, making insertion and removal of bladders a bit cumbersome. And, the abundance of straps and technical features like lash points and trekking pole attachments can feel excessive for shorter hikes. But when you’re on trail and need a bag for moving fast and staying efficient, the Protium 27 is a great pick.

Weight and Compressibility

The Rab Protium 27 strikes an impressive balance between weight and functionality, making it a versatile option for all-day treks. At 2 pounds, 6 ounces, the pack feels very manageable even during long hikes. Ian hiked the famous Devil’s Garden Trail in Arches National Park, Utah in winter conditions with this pack fully loaded. Even with the scrambles, ice, slick rock and sketchy slopes, this pack felt fairly light and agile, even packed with lots of layers and bulky gear. 

However, its weight is on the heavy side compared to many bags on our daypacks list. It’s also not the most compressible option. The sturdy foam back panel prevents the bag from rolling, folding, or flattening for easy storage.

Our team gravitates towards more minimalist 20-24 liter models for the majority of our dayhikes, so the Protium can feel a bit excessive, especially if we’re only out for just a few hours.

Durability

The Rab Protium 27 is built like a tank for the backcountry. While Ian’s only put about 200 miles on his pack, he hasn’t babied it in the slightest – it’s been dragged across sharp rocks, snagged on gnarled junipers, and stabbed by prickly cacti in Utah slot canyons. He’s also taken it on over a dozen rugged off-trail routes in the Colorado high country above 9,000 feet. Crafted from tough nylon and polyester, it’s proven to be both abrasion- and puncture-resistant. Side mesh pockets and a large mesh stuff pocket have yet to show any signs of fraying, and have avoided stretching from heavy bottles. The zippers, nylon straps, and sturdy plastic hardware remain unscathed after heavy use as well.

We’ve found little to fault with the Protium 27 when it comes to durability. It’s worth noting the rugged build makes it heavier than minimalist daypacks. But for those who need a bombproof pack for slightly heavier and bulkier gear, the Protium 27 may be exactly what you’re looking for.

Should you buy the Rab Protium 27 Daypack?

The Rab Protium 27 is a great choice for hikers and adventurers who want a rugged, versatile daypack that can handle diverse year-round conditions and challenging terrain. Its 27-liter capacity accommodates gear for longer day trips or bulkier cold-weather layers, and the highly adjustable frame and straps make it adaptable for most people for many miles. However, the Rab Protium 27 is not the best fit if your priorities lean toward ultralight simplicity or you need a pack for casual, everyday use. It’s also one of the most expensive packs we’ve tested. But when it comes to premium daypacks, the Protium 27 is a smart choice when you need to carry more gear or tackle a technical route in unpredictable weather – making it one of our new favorites.

What other day packs should you consider for hiking?

If you’re not sold on this new day pack, please see our complete guide to the best daypacks for hiking.

Gregory Zulu 30 Review: We recommend this one for hikers who need even more room for group adventures, heavy or bulky gear, or quick overnights..

REI Trail 25 Review: The Trail 25 is smart pick if you need a smaller, affordable option with solid technical features that works for city and backcountry.

Osprey Stratos 24 / Sirrus 24 Review: These packs are a great for hikers who want the best of the best for durability and comfort in a smaller, higher end format, even if it means sacrificing a bit of space and affordability.