Modularity Meets Winter – Kollen by Tiril Eckhoff

At Kastel, we’ve always believed that smart design should do more. One shoe should adapt to your day—not the other way around. That’s where modularity comes in.

Over the years, we’ve explored modular thinking in different ways. Not to follow a trend, but to solve a problem: how do we make shoes that last longer and do more, without asking customers to own more?

With Kollen, we’re applying that idea to winter.

Designed in collaboration with Olympic gold medalist Tiril Eckhoff, Kollen is a waterproof winter boot built with one goal: maximum versatility. Each pair includes a padded, insulated shaft that attaches securely at the cuff. When the weather turns cold or snowy, you add the shaft for full winter protection. When conditions clear up or you head indoors, you remove it—and you’re left with a sleek, everyday boot that’s lighter and more casual.

The removable shaft works like a puffer jacket for your lower legs—adding both warmth and function, without needing a second pair of shoes.

With modularity, we make one boot that performs like two. Less bulk. Less waste. More wear.

This is only the beginning.

Modular thinking is shaping how we design the future of Kastel—alongside partners like Tiril, who knows winter better than anyone.