Welcome to the "WHY DO WE?" video series.
Every stitch and square inch of our K4 Packs are designed on purpose and built for a purpose. The videos in this series will go behind the design to explain why we build our packs the way we do.
In this video, we discuss why we use dual-density foam in the K4 Frame's Lumbar Pad, how the foam performs with different loads, and options to change the feel of the lumbar pad for certain body types.
Comfort and support with every load.
When designing a backcountry hunting pack frame, you have to build something comfortable and supportive across an incredibly wide range of loads. One minute the K4 Frame could be carrying 15 pounds while a hunter moves "fast and light" in pursuit of an animal, and an hour later, the frame could be carrying 115 pounds as a long packout begins.
We use dual-density foam in the K4 Lumbar pad to provide a dynamic layering strategy of softer foam that feels plush with lighter loads, backed by a more structured and supportive foam that won't over-compress as loads get heavier.
A foam that breaks in, not breaks down.
There are a lot of cheap foams on the market, and it is an area where it would be easy to cut corners (and increase margins) when building our packs.
Lesser foams will feel their best on Day 1, then lose structure and performance rather quickly. The foams that we use require a slight break-in from Day 1, then provide long-lasting comfort and performance.
If you wear your K4 Frame for 10-15 miles of weighted hiking and still feel that the Lumbar Pad is too firm, let us know and we can provide a softer lumbar foam for you. The vast majority of our customers should stick with the stock (blue) foam, but there are some body types — especially those with a very flat back profile — that may find the best comfort with our softer (white) foam option.
Foam, Fabric, & Fit
Beyond the foam itself, the surface fabric of the K4 Lumbar Pad is a key component of the pack's performance. The surface fabric we use features patterned grip text, which helps the pack stay and place and prevents issues with "sag" in the lumbar pad. (Side note: too much grip on the lumbar fabric creates issues with abrasion and irritation, so the fabric we use has been carefully selected and refined over extensive testing.)
In addition to lumbar foam and lumbar fabric, the fit of the hipbelt is absolutely critical for proper performance. If you haven't already, be sure to check out the first installment of the Why do we? series, which is all about K4 Hipbelt Design & Fitting.