He talks about Kortel design:

I've been using Kortel's Kliff III and Kompact Bag for a while now, and since my main activity is walking and flying, they're the ideal companions for me. The combo of the two products allows me to climb light at takeoff, even with my cross-country glider. I use the Kompact as a sock when I'm flying in a cocoon on big days, and I convert it into a bag when I'm doing a bit of distance flying in the evening, sitting in my Kliff III. Light, minimalist and versatile are, in my opinion, the three adjectives that best describe these two products, which fit in perfectly with my vision of free flight. In short, I'm delighted to be able to combine lightness on the way up with comfort on the way down.