Featured Review · Exo Mtn Gear · Packs
Exo Mtn Gear K4 3600 Review — A Carbon-Frame Hunting Pack Built to Carry the Elk Out, Drawn and Loaded
Our Rating
Current Price
- System
- K4 3600 bag + K4 frame + K4 Lid
- Capacity
- 3,620 cu in bag (about 59 L); 4,268 cu in with lid (about 70 L)
- Weight
- Bag 2 lb 1 oz; bag + frame 5 lb 0 oz; with lid 5 lb 8 oz
- Frame
- Carbon-fibre stays, integrated load shelf
Pros
- Carbon-fibre frame with a load shelf, rated for 150+ lb — and the bag unclips so meat rides between bag and frame
- 5 lb 8 oz for bag, frame and lid: light for a true meat hauler
- 3,620 cu in bag plus a 650 cu in lid that doubles as a compression panel for antlers and skulls
- Huge, well-padded hipbelt with laser-cut MOLLE and a cam buckle; four frame heights and five belt sizes
- Roll-top plus a full-length side zip, front stretch panel, scope-sized pleated pockets and stretch pockets for a tripod or poles
- Made in Boise, Idaho, with a lifetime guarantee for the original owner and a 30-day trial
Cons
- US$679.99 is a lot of money for a pack
- Sizing matters: you choose a frame height and a belt size, and reviewers have had to swap belts
- Overbuilt for light day hunts or ultralight hiking — it earns its weight when it is carrying meat
- One review notes the bag's narrower bottom makes very bulky items awkward, and another wanted more straps for loose meat
- We have fitted and walked with it, but have not yet packed an animal out — that is coming this season
A deer is a heavy, awkward thing to move. An elk is four or five of them. Whatever pack you carry in to a backcountry hunt, the real question is what it feels like on the way out — with a hindquarter, a pile of boned-out meat in game bags, or a set of antlers sticking up over your head.
The Exo Mtn Gear K4 3600 Pack System is built around that question. It is a 3,620 cubic-inch bag — 4,268 with the included lid — on a carbon-fibre frame with an integrated load shelf, rated by Exo for 150+ pounds. The bag unclips from the frame so meat can ride between bag and frame, right against your back, and the lid turns into a compression panel for skulls and antlers. The whole system — bag, frame and lid — weighs 5 lb 8 oz. It is sewn in Boise, Idaho, and costs US$679.99.
Ours is a Ranger green K4 3600 with a Medium hipbelt. We have unboxed it, fitted it, and carried it around the farm and through the blueberry rows; it is going on our hunts this fall. This review covers everything we can show and measure now — all 74 of our photos — plus interactive drawings of what fits inside, how it carries deer and elk, antlers, a bow, or a rifle on the side, and a meat pack-out planner built from published deer and elk yields.
At a glance
A note on what this review is not: our box also contained Exo’s K4 Quick-Release Rifle Carrier, a separate US$39.99 accessory. We are not reviewing the rifle carrier here. We do show, in the drawings below, how a rifle rides on the side of the K4 — because that is one of the most useful things the pack can do on a rifle hunt.
Who Makes It
Exo Mtn Gear was started in 2014 by two hunting partners, Steve Speck and Lenny Nelson, who wanted a pack that carried like a light internal-frame backpacking pack but hauled meat like an external frame. It is still a small company — Exo says about seven full-time staff — and the packs are designed, built and shipped from Boise, Idaho. It sells direct rather than through stores. The K4 is the fourth generation of its frame system, and the 3600 is the mid-size bag in the range: big enough for a three- or four-day hunt, small enough to hunt out of every day.
Unboxing
The Frame, Belt and Harness: Where the Money Goes
The bag is the part you see. The frame and hipbelt are why people pay for an Exo. Two carbon-fibre stays run the height of the frame, stiff enough to put a heavy load onto your hips, with smaller cross-members that let it flex a little with your body. At the bottom is the load shelf that meat sits on. Four frame heights (22, 23.5, 25 and 26.5 in) each give about six inches of torso adjustment, and the belt comes in five sizes.
Where the 5 lb 8 oz goes
Exo publishes bag-only (2 lb 1 oz), bag + frame (5 lb 0 oz) and bag + frame + lid (5 lb 8 oz). The frame and lid figures are the differences between those numbers. Bars show share of the total.
More than half the weight is the frame and suspension — and that is the right place for it. On a light day the frame is overkill. With 80 pounds of elk on it, it is the only thing that matters.
Sizing: the one thing to get right
Exo picks the frame height from your height, not a torso measurement, and every frame has about six inches of adjustment. Where two frame heights overlap, Exo suggests the shorter one for lean builds, longer legs, thick timber and day hunts, and the taller one for broad or barrel-chested builds, longer torsos, open country and backpack hunts with 35+ lb.
The hipbelt is sized at the iliac crest — the top of your hip bone, found by putting a finger an inch below your navel and feeling outwards. Measure around your body there. Small is 30–34 in, Medium 34–38 in. Exo is firm: don’t round up, and don’t use your pant size. At least one reviewer we read ended up swapping belt sizes, which is easy because the belt detaches from the frame — but measure carefully first.
The K4 3600 Bag and Lid
The bag is MIL-SPEC 500D Cordura with YKK zips. It opens at the top with a roll-top that also compresses the load, and down the side with a full-length straight zip, so you can reach the bottom of the bag without unpacking it. The K4 Lid sits over the roll-top and adds about 650 cu in in two compartments.
Zips, pockets and the details
Explore It: Every Pocket and Strap
Tap a feature — or tap the drawing — to see where it is and what it is for.
The K4 3600 seen from behind the hunter. Tap any feature to highlight it.
Pack It: What Fits in 3,620 Cubic Inches
Exo builds the 3600 for hunts of up to three or four days. Tap gear in and out to see how the bag and lid fill — or start from a preset. Items marked outside ride in the side pockets and do not use bag space.
Bag and lid capacities are Exo's figures (3,620 cu in bag; the lid adds about 650). Gear volumes are our own rough estimates for compressed, typical backcountry kit — your sleeping bag and shelter will make the biggest difference. A 3 L bladder is 183 cu in.
Two things from our earlier reviews belong in this pack. The Sawyer Squeeze lives in the lid, and a set of Eberlestock Cirrus dry bags inside keeps the sleeping bag and spare layers dry — the K4 is Cordura, not a dry bag, and one reviewer saw water get in at the seams in long, heavy rain.
Seven Ways to Carry It
This is where a frame pack earns its price. Pick a setup to see how the K4 3600 changes shape — from a hunting pack, to a meat hauler, to a frame carrying a whole elk quarter.
Schematic drawings, not to exact scale. Carry methods are from Exo's product description and reviews of K4 packs. The Quick-Release Rifle Carrier is sold separately and is not covered in this review.
How Much Deer or Elk Can It Carry?
Exo rates the K4 frame for 150+ pounds. That is a statement about the frame, not about you. The planner below uses published yields to show how much meat an animal really is, how many trips it takes at a load you choose, and how each trip compares with the frame’s rating and a common guideline of no more than about 40% of your body weight.
Where the numbers come from. Elk: onX's averages — a bull yields about 218 lb of boned-out meat and a cow about 169 lb; our bone-in figures add up onX's mid-range quarter weights plus backstraps (bull: 2 × 70 lb front, 2 × 80 lb hind, 22 lb backstraps; cow: 2 × 41 lb, 2 × 65 lb, 16 lb), and a bull's head and antlers is onX's 40 lb example. Deer: Deer & Deer Hunting's rule of thumb that realistic boneless yield is about 35% of field-dressed weight, and carcass weight is about field-dressed ÷ 1.33. Real animals vary a lot. The 40% of body weight guideline is from onX. Always check your local rules on boning out and evidence of sex.
To put the default numbers in plain terms: a big whitetail boned out is roughly 60-some pounds — one comfortable trip in the K4 3600, meat between bag and frame. A boned-out bull elk is over 200 pounds of meat before the head: three or four trips for one hunter at a sensible load, or one long day for two. Exo’s frame will take a heavy load; the planner is a reminder that the person under it is the limit.
Out at the Farm
Wearing It
First impressions with a light load: the belt is the star. It is broad, firm and well shaped, and it sits on the hips rather than the waist. The harness stays out of the way of your arms, and the pack is narrow enough that it does not catch on the blueberry bushes. With almost nothing in it, it is more pack than you need — which is exactly what reviewers say. The real test is a loaded pack-out, and that is coming.
What Reviewers and Owners Say
We have not packed an animal out with it yet, so here is what people who have are saying, summarised in our own words.
"The most comfortable heavy hauler"
After three months with the K4 3600 and lid, Carryology's reviewer called it the most comfortable heavy hauler he has owned, with most of the weight going to the hips and loads over 80 lb carried. Praise for the build, the scalability of the K4 system, the warranty and the US manufacture. Against it: the price, and it is heavier and less nimble than an alpine pack. A specialist pack, not a do-everything one.
The hipbelt makes the difference
Tested on the bigger 7200 bag, but on the same K4 frame and belt: 90–100 lb each on a steep, off-trail mule deer pack-out, and a belt the reviewer says makes 60 lb feel like 40. He likes the quick meat shelf with cold fingers. His complaints: he would like more than two compression straps for loose meat or a head, colour-coded buckles, and one buckle prong broke — a US$3 replacement.
"An extension of my body"
Loads, including elk antlers, stayed balanced and centred; the narrow frame left full range of motion; switching to meat-hauling mode took seconds. The reviewer was between belt sizes, chose Small, and Exo sent a larger belt that swapped on easily. He would like easier access to the bag zip when the front straps are loaded.
Bulls, goats and mule deer
Owners report packing out bull elk, a mountain goat and boned mule deer with K4s. One compared the belt favourably with Stone Glacier's — wider, better padded and less inclined to slip. Several run the 3600 without the lid for head and brush clearance, and one keeps loads at about 110 lb as a smaller person.
Comfortable under load
On Exo's own site, 239 of the 244 reviews of the K4 3600 are five stars, with four four-star and one two-star review. The repeated theme is comfort and stability with heavy loads — one buyer says it makes 100-pound pack-outs "suck just a little bit less".
The picture is consistent. The frame and belt are the reason to buy a K4, and they carry heavy, awkward loads better than almost anything else. The complaints are about price, getting the size right, and small details — one review finds the narrower bottom awkward for very bulky items, and another wants more straps for loose meat.
Pros and Cons (the Honest Version)
What it does well. A carbon-fibre frame with a load shelf, rated for 150+ lb, that lets meat ride between bag and frame or on the bare frame. A 3,620 cu in bag and 650 cu in lid for hunts of up to four days, with a roll-top, a full-length side zip, a front stretch panel, scope-sized pleated pockets and stretch pockets for a tripod. A lid that doubles as an antler panel. A big, comfortable hipbelt with MOLLE. All of it in 5 lb 8 oz, sewn in Boise and backed by a lifetime guarantee and a 30-day trial.
Where to go in with your eyes open. It is US$679.99. You have to measure carefully for frame height and belt size. On light day hunts it is more frame than you need. One review finds the bag’s narrower bottom awkward for very bulky items, and another wants more straps for loose meat or a head. And we have not yet loaded it with an animal ourselves — that is coming.
Who Should Buy It
Buy it if you hunt elk, mule deer, sheep or goats in the backcountry, if you expect to pack meat on your back, and if you want one pack that can be your three-day hunting pack and your meat hauler. Buy it if you are tired of a pack that is comfortable until the meat goes in.
Look elsewhere if you mostly hunt from a stand or close to the truck, if you never carry more than 30 pounds, or if every ounce matters more than load-carrying. A lighter frameless pack, or a daypack and a game cart, will serve you better and cost less.
Final Verdict
The Exo Mtn Gear K4 3600 Pack System is a hunting pack designed from the pack-out backwards. The carbon frame, load shelf and big hipbelt are built to put heavy, awkward loads on your hips; the bag swings out of the way so meat can ride against your back; the lid turns into an antler panel; and a bow or a rifle rides on the outside. Everything we have seen in the box and on our backs matches what reviewers and owners report. It is expensive, and it rewards careful sizing — but for backcountry hunters who intend to carry an animal out, it is the kind of pack you buy once.
Rating: 4.8/5 Stars
Coming Up: In the Field
The K4 3600 is going on our hunts this season, and you will see it in our upcoming hunting posts — loaded for multi-day hunts, carrying meat out between bag and frame, and hauling whatever we are lucky enough to pack home. We will report how the frame and belt feel under real weight, how the Ranger green holds up, and add what we learn here.
First hunt: the K4 3600 came along on our morning glassing hunt above the Chehalis cutblocks, carrying the blaze vest under its lid.
Brands sometimes provide samples for review. Hunt & Live writes its honest opinion either way — gear that doesn’t earn its keep doesn’t get a recommendation.