They seem high quality and durable. Grippy sole too. The toe is a little loose, but very grippy laterally and at the heel. I had to get a size M for about 39 ski boots, the size S was too small.
Verified buyer

Especially the soles of racing-style cross-country ski boots are minimal and slippery, and may not withstand long distances on surfaces such as coarse gravel used for sanding. The Walking Coverboot is designed to provide grip and protect the soles of your boots.
Thanks to their flexible structure, Walking Coverboots are easy to pull on and take off.