Stone Glacier Sky 5900 vs Exo Mtn Gear K4 5000
Quick take: The Exo Mtn Gear K4 5000 costs $25 less; the Stone Glacier Sky 5900 carries more (96 vs 93 liters); the Stone Glacier Sky 5900 is lighter (5.5 vs 5.8 lbs).
| Spec | Stone Glacier Sky 5900 | Exo Mtn Gear K4 5000 |
|---|---|---|
| Price | $725 | $700 |
| Rating | 4.9★ (252) | 4.9★ (529) |
| Type | Hunting Pack | Hunting Pack |
| Frame Type | External Frame | External Frame |
| Capacity | 96 L | 93 L |
| Weight | 5.5 lbs | 5.8 lbs |
| Max Load | 150+ lbs | 150+ lbs |
| Torso Fit | Hook-and-loop micro-adjustable yoke; Xcurve frame suits torsos ~20 in and up (Krux covers shorter); 3 belt sizes 28–37+ in | 4 frame heights (22–26.5 in) with adjustable harness, 5 hipbelt sizes XS–XL |
| Material | CORDURA 500 and X-Pac laminate, YKK #10 zippers, Duraflex hardware; made in USA | MIL-SPEC 500D CORDURA with YKK zippers; built in Boise, Idaho |
| Back Panel | Xcurve carbon-stay frame with curved profile, adjustable lumbar pad, and integrated fold-out load shelf | K4 carbon-fiber-stay frame with integrated load compression and flap-style load shelf |
| Adjustable torso | Yes | Yes |
| Ventilated back | No | No |
| Raincover included | No | No |
| Hipbelt pockets | No | No |
| Removable lid | Yes | Yes |
| Hydration sleeve | Yes | Yes |
| Fits BV500 bear can | Yes | Yes |
| Warranty | Lifetime warranty against defects in materials and workmanship | Lifetime guarantee against defects, plus 30-day trial period |
Pros & cons
Stone Glacier Sky 5900
- ✓The 150+ lb load rating is real-world verified — GearJunkie packed 110+ lb elk loads and said it 'carries like a dream with heavy weight', a claim Rokslide owners routinely back up.
- ✓Bivy-mode compression is the party trick forum users cite most: the 5,900 ci bag cinches to 4,300 ci with 'zero wiggle', so it genuinely replaces a day pack.
- ✓The fold-out load shelf adds 2,500+ ci between bag and frame (8,000 ci total), keeping bloody quarters off your camp gear entirely.
- ✓Full front-panel horseshoe zipper gives duffel-style access to the main bag — a major livability win over roll-top-only rivals like the Kifaru 357 Mag.
- ✓The 22-inch vertical front pocket swallows a full-size spotting scope, and glassing-heavy hunters call it the best stock optics solution in the category.
- ✓At 5.5 lbs complete (2 lb 4 oz bag), it undercuts most 150 lb-class haulers — the usual Rokslide summary is 'lighter than the competition but extremely tough'.
- ✓Scheels buyers rate it 4.9 stars across 252 reviews with zero one-star ratings, and Stone Glacier's fast shipping and lifetime warranty draw consistent praise.
- ✓Hook-and-loop harness micro-adjustment lets you fine-tune torso length continuously instead of in fixed half-inch steps.
- ✗Hipbelt pockets cost extra, and Rokslide users say Stone Glacier's accessory hip pockets run small and 'fight back' when zipping them mildly full.
- ✗Organization is deliberately minimalist — one big cavity plus a few externals — so hunters coming from pocket-rich Mystery Ranch designs face a packing-cube learning curve.
- ✗The Sky Lid is the most common gripe in reviews: floppy when open and fiddly to reattach, with GearJunkie calling it the only thing they 'don't really love'.
- ✗$725 before add-ons (lid pockets, hip pockets, rifle sling) — real-world builds push $800, roughly $200 over a complete Metcalf 75.
- ✗The 5,400 ci main bag is 'just barely big enough' for cold-weather multi-day hunts; Rokslide steers week-plus trips to the Sky Guide 7900.
- ✗The Xcurve's pronounced curve fits torsos 20 in and up with rounded backs — flat-backed or shorter hunters must switch to the Krux, making remote fit selection a gamble.
- ✗Stone Glacier's rifle-carry solution trails Kifaru's Gun Bearer in reviewer preference, so many owners bolt on third-party weapon carry.
- ✗Dropping the bag to deploy the load shelf means unbuckling and re-tensioning straps — slower meat-mode transitions than Exo's flap-style shelf.
Exo Mtn Gear K4 5000
- ✓Rokslide's multi-tester review called the K4 'the most comfortable pack tested' against the industry's best, crediting the custom carbon-stay frame and redesigned harness.
- ✓Fit options lead the category — four frame heights (22–26.5 in) and five hipbelt sizes (XS–XL), backed by a 30-day trial, versus pick-a-curve guesswork with Stone Glacier's Krux/Xcurve.
- ✓Organization is the K4's calling card: horseshoe zip into the main bag, stretch front panel, full-length zippered side pockets, and laser-cut MOLLE — owners say it's the easiest flagship pack to live out of.
- ✓The flap-style load shelf deploys without pulling the bag off the frame, making day-pack-to-meat-hauler transitions faster than Stone Glacier's unbuckle-everything approach.
- ✓The included lid adds ~650 ci and the price includes the complete system — no a-la-carte lid or frame math like Kifaru builds.
- ✓A dedicated hydration compartment with a drain grommet keeps a leaky bladder from soaking your sleep insulation, a detail forum users repeatedly call out.
- ✓Owners rate it 4.9 stars across 529 reviews on Exo's site (98% five-star), and the Boise-based customer service earns Rokslide praise rivaling Mystery Ranch's.
- ✓Integrated bow and rifle carry work stock, and treadmill-style testing threads report no harness slippage running uphill with 30+ lb loads.
- ✗The bag tapers narrow at the bottom — Rokslide users report bulky sleeping bags like a Western Mountaineering Kodiak in its stuff sack fight to fit.
- ✗Several owners in the long-running K4 thread report harness or hipbelt slippage once loads pass roughly 60 lbs, requiring re-tensioning on pack-outs.
- ✗Side pockets use a single zipper that interferes with the lid when it's fitted — a two-zip design is a common owner wish.
- ✗Bow Spider users note the mount's metal clips don't line up with the K4 hipbelt MOLLE spacing, forcing workarounds for a popular accessory.
- ✗Hipbelt pockets aren't included — the MOLLE belt is bare until you buy Exo's add-on pouches, unlike some competitors' stock belt storage.
- ✗At 5 lb 13 oz complete with lid, it's the heaviest of the big-three frame systems — about 0.3 lb over a Sky 5900 and half a pound over a Metcalf 75.
- ✗The lighter K4X update (about 1 lb savings in prototypes) has limited release in summer 2026 with full launch in 2027, so buyers today are getting last-generation materials.
- ✗Exo sells essentially direct-only, so outside the 30-day trial there's no trying one on in a store the way Scheels stocks Stone Glacier and Mystery Ranch.