K4 Pack Systems — Behind the Design

K4 Pack Systems — Behind the Design

Above: Testing K4 Prototypes on the 2022 Death Hike in the Chugach Mountains of Alaska


When we launched our all-new K4 Pack Systems in late-March of 2023, it wasn't the beginning of something new. Rather, it is just a transition in time when years of focused development and relentless testing culminate in our ability to share K4 Packs with anyone that wants to participate in our singular mission to build and hunt with the best backcountry pack systems possible.

Before there was K4, there were countless ideas, prototypes, and tests. Before we put 150 prototypes of K4 Packs in the hands of hunters in 2022, we hiked thousands of miles and hunted across the country in 2019, 2020 and 2021 to test new materials, new ideas, and new designs.

If you want a glimpse of what we have been up to for the past 3+ years as we have worked on the development of K4, we want to share some of that with you today.

In the video below, Steve shares a look at some of the pre-K4 prototyping and testing that he was doing on his 2021 sheep hunt in the Frank Church Wilderness. (Listen to that hunt story.)

Keep in mind that the production K4 Pack Systems have changed in numerous ways, compared to the early prototypes shown in this video.

"My 2021 Frank Church sheep hunt was a great test of the early K4 prototype frame that I had been working on. After the 21+ mile packout, I was very excited about the performance of it.  I knew the core design of the frame was there and it was just a matter of polishing up all the little details over the next 18 months." —Steve Speck, owner of Exo Mtn Gear

A Glimpse of pre-K4 Prototyping & Testing

The photos below are from 2019, 2020, 2021 and early 2022 testing and development of pre-K4 prototypes. This is only a small glimpse at the hundreds of photos we have that document the countless prototypes, materials, and designs we tested.

In the summer of 2022 we finalized the final K4 Prototypes, which were put on the backs of 150 hunters for them to test throughout their 2022 big game hunts.

2019 — Squadron Frame Panel

June of 2019 (before we even launched K3) — One of the first frame panel concepts built with a proprietary laminate fabric from Brookwood called Squadron, which is built with 1000d Cordura laminated to 500d Cordura. With Squadron’s incredible strength and durability, we are able to use laser-cut Squadron to build the K4 Frame panel and the K4’s MOLLE panels — offering lighter weight, less bulk, and higher-strength than traditional materials and construction methods.  Steve hunted with this prototype for most of his hunts in 2019.

Laser-cut MOLLE panels on a Prototype Hipbelt

January 2020 — We begin to explore how laser-cut MOLLE panels would work for accessory mounting on a prototype hipbelt. (Ivory Holster shown here).

The performance of this hipbelt was actually quite bad and we had to go back to the drawing board on how we could execute this option.  We learned a lot of lessons that we applied to the final designs through testing and failures during the K4 development process.  

2020 Frame Panel Concept

February 2020 — The Frame panel concept built with laser-cut Squadron starts to get more refined.  We start testing a new concept for shoulder harness adjustment and attachment.

2020 Nalgene Holder Prototype

April 2020 — An early prototype of a Nalgene holder that was integrated into the bag and supported by the frame's hipbelt. This design changed dramatically and for K4 we offer an independent Nalgene holder accessory, which the K4 Hipbelt was purpose-built to integrate with.  Also in the photo is one of the many spacer mesh fabrics we sampled on the shoulder harness, to see if we could find something we liked better than the spacer mesh we used in K3.  In the end, we continue to use the same spacer mesh in K4, which has performed exceptional in the thousands of K3 packs out there.

2020 Death Hike

July 2020 — Steve tests a prototype frame on the 100-mile Death Hike in 2020.

2020 Prototype Bag

Jake Models a Prototype Bag

July 2020 — A prototype bag design being sewn by Enessa, and then modeled by Jake in the Exo warehouse. Steve would ultimately take this bag to Alaska on his 2020 Dall Sheep hunt. In this design, we played with a more streamlined bag to save weight, but after using this bag design on several hunts the lack of pockets made the pack a lot less functional in real world scenarios.  

Steve Tests a Prototype in Alaska

August 2020 — Steve tests the prototype frame and new bag on an Alaskan Dall Sheep hunt. The frame performed really well on this hunt and in other testing, but we didn't feel like it was enough improvement over the K3, so we went back to the drawing board to test new ideas.

Early Prototype with Independent Vertical Stays

September 2020 — The first prototype frame with independent vertical stays — what is now a core aspect of the K4 Frame design. This was an all new concept, completely different than K3. These early versions used the same Titanium tubing that was in K3 frame, but the round tubing proved to be problematic in the independent stay design so we started looking at flat options.

Elk Packout with a Prototype

September 2020 — Steve uses the prototype frame design (from the previous photo) to pack out his archery elk from Idaho. This was the first real mountain test of a design that used two independent vertical stays versus the once-piece construction of the K3 Frame. Performance of the frame was great, but more work was needed on the hipbelt design.

Steve Hikes with His Son, Joey

October 2020 — Always looking for an excuse to hike and test frame concepts Steve tests a prototype by strapping a child carrier to the frame and taking his son for a hike.

Early Prototype Frame Example

March 2021 — We continue to evaluate different ways of constructing the frame's upper panel. You can also see see the first use of flat stays instead of the round Titanium tubing. We used Aluminum early on, as it was easy to bend and change the shape as we worked to refine the exact frame profile we needed.

Steve on the 2021 Death Hike

2021 Death Hike in the Frank Church

April 2021 — Mark and Steve test the flat stay prototype frame on the 2021 Death Hike in the Frank Church Wilderness. With 50lb packs and quite a few miles of off-trail hiking and snowshoeing, we were both very excited about how the frame performed. This trip was a really great test of the concept.

2021 Hipbelt Pattern

Sewn Hipbelt Prototype

May 2021 — After countless designs, foam samples, shapes and construction methods, the pattern of what would become the K4 Hipbelt design starts to take shape. There were certainly more revisions after this, but the concept really started to come together here.

Post-Hike Comparison of K3 and a K4 Prototype

June 2021 — Steve would take before and after photos when completing training hikes, noting how much the position of the pack had visibly shifted after hiking with heavy weight, such as this 110lb load.  

In the photo above, a K4 prototype is on the left and the K3 is on the right. Both packs were loaded with 110lbs and Steve would then hike the same 2 miles, not making any adjustments on the pack during the hike. While the K3 was still comfortable, you can see how the K4 prototype stays up in the lumbar pocket and on the hips better. This is most visible if you look at the load lifter angle — both frames are exactly 25" tall, yet the K4 is sitting up much higher.  

2021 Prototypes Ready to Ship

August 2021 — Based on our development and testing to this point, we were confident that we had something better than K3 in regards to the prototype frame's performance. But that was all based on our internal testing. We decided to make 50 of these new prototypes and send them out for the 2021 hunting season to get feedback from other hunters. We initially called these frames "PIKA" after the marmots that live their entire lives above treeline. We also experimented with very different bag designs throughout this time.  

2021 Sheep Packout

September 2021 — Steve and Tyler pack 21+ miles out of the Frank Church wilderness with PIKA prototypes after a successful once-in-a-lifetime sheep hunt. This 81lb, 2-day packout was a fantastic test of what the new frame was capable of.  

Mark hunts with a prototype bag in 2021

October 2021 — A good look at a prototype bag, which had a unique zip-access design for the main bag, one of the original Nalgene holder concepts, laser-cut MOLLE on the hipbelt, and zippered side pockets.

Mark's 2021 Bull Elk Packout

October 2021 — Mark packing the last load of his 2021 Idaho bull. Mark and Steve used PIKA prototypes to pack out two bulls in two days on their 2021 elk hunt.

Dioni's 2021 Buck

October 2021 — Dioni packs out a monster buck while testing a PIKA prototype.

Big Bull Elk packed-out on a PIKA Prototype

October 2021 — Anthony's big bull on a PIKA prototype for a long, heavy, dark packout.

PIKA Prototype on Kodiak Island

November 2021 — We had seven guys run PIKA prototypes on a challenging trip to Kodiak Island in November of 2021.

2021 Revised Frame Prototype

End of 2021 — Throughout the year we continued to develop and refine the "PIKA" frame. There are major changes between the frame prototypes of early 2021 and late 2021.  In every revision the frame kept getting better and better.

Spacer Mesh Abrasion

January 2022 — The PIKA frames performed exceptionally well throughout 2021 and the feedback from the 50 hunters was universally positive. We interviewed each of them to get as much feedback about their experience as possible. After a full hunting season, we had a handful of things to see if we could improve upon within the frame and we knew we had at least one more year to keep refining. One example of things to address was the thicker spacer mesh on the PIKA prototypes, combined with the more rigid connection of the harness to the frame, the material could experience abrasion if the user had a bino harness that had any rough edges on it.

Testing Never Stops

January 2022 — Testing never stops. After hunting season ends, the year-round testing continues for Steve.

Climbing with Prototype Frames

Prototype Testing in February of 2022

February 2022 — Always taking advantage of any available time, Steve and Mark went for hikes every morning before the Utah Hunt Expo to get some prototype testing in. On these specific hikes, Steve was having Mark test out different plastic thickness behind the lumbar pad to see if he had a preference.  By playing with different thickness of plastic here we could really tailor the exact pressure we wanted in the lumbar pad.  

Prototype Bag-to-Frame Connection Design

March 2022 — Working on new concepts for the bag-to-frame attachment, and also evaluating material options, such as XPAC fabrics and AquaGuard zippers.  You can also see the shoulder harness with a solid stretch fabric versus spacer mesh. While this worked alright, we all preferred the breathability and quick-drying benefits of spacer mesh.

Performing a "Shower Test" on Different Materials

April 2022 — Performing one of many tests on waterproofing as we evaluated materials, zippers, and construction methods.  After all of our testing we came to the conclusion that 500d Cordura had the best overall performance when it came to durability, weight, quietness and water resistance.  Seams are the weak point and even with 100% waterproof fabrics there was no substantial difference in the amount of water that made it into the pack after these shower tests.  

Prototype Nalgene Holder

April 2022 — Refining the design of an independent Nalgene holster after our testing in 2021 showed that there were too many drawbacks when trying to integrate the Nalgene holder as part of the bag design.

Hauling a Bear with a Prototype Crib and Frame

Steve Packs his Spring Bear

Mark Packs his Spring Bear

May 2022 — After doubling-up on bears on the first day of their spring bear hunt, Steve and Mark use prototype frames, bags, and Cribs to haul the bears out of the backcountry. With two bears loaded and a long hike out, it was a great real world test of the frames. The frame is getting very close to becoming final at this point.  

Steve on the 2022 Death Hike in Alaska

June 2022 — The 2022 Death Hike in the Chugach Mountains of Alaska was the final trip to test all of the last designs tweaks made before building 150 K4 Prototypes that would be tested by hunters across the USA, and internationally, throughout the fall of 2022.  We had most of the guys running prototypes on this hike.  

2019-2023 - A long journey

What we shared above is just a small sampling of the hundreds of photos that document all of the development from 2019-2022 as we built what is now our all-new K4 Pack Systems.

Our singular mission has always been to build the absolute best mountain and backcountry hunting packs that we could. To say that we are excited to fulfill that mission as we launch K4 would be a massive understatement. It has been a long process over the past several years, but we are incredibly proud of the product that has been created from all of the design, testing, and revisions.

Continue the Journey: Behind the Design — Part 2

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