Qiviut (pronounced “kiv-ee-ute”) is the name for the downy hair of the musk ox. It is the warmest fiber in the world — about eight times as warm as sheep’s wool. Musk oxen live in Alaska and Canada where temperatures sometimes drop to –100ºF (-73ºC), so they need protection. The Inuktitut name for the musk ox is “umingmak” meaning the …

Because I’ve been testing wool products for about ten years, I’ve tried many brands of merino wool pants. These are the software ones I’ve found: 100% Merino Wool Warm Up Sweatpant by Woolly Woolly just introduced this new sweatpant called a “Pro-Knit Warm Up Sweatpant“. The “pro-knit” fabric is an 18 micron merino that is ” woven into a compact …

These hats are made of qiviut (musk ox wool), yak wool, bison wool, alpaca and merino. They are the warmest I’ve found:

Merino wool shorts only made by a few companies so they are somewhat difficult to find.

These are the warmest hoodies I could find in 2019:

These are the warmest sweatpants I’ve found this year.

This is a list of companies make clothing with natural materials:

This is a list of men’s clothing that features superfine and ultrafine merino wool:

These are the best merino wool polo shirt’s I’ve found this year:

In terms of fineness, any wool fiber that has a diameter of 20µ (microns) or less will feel very soft to the touch.

Camel wool is a very soft, insulating fiber. It ranges in size from 15 to 22 microns — putting it in the ultrafine or superfine categories.

Bison down is a very warm, insulating fiber. It is also very durable for such a soft fiber.

Yak down is a very warm fiber that’s also lightweight and soft. It’s a more affordable alternative to the rare qiviut (musk ox down). Yaks are primarily raised by nomadic Tibetan and Mongolian families. Their wool is combed once per year in the springtime. Some advantages of yak wool: Yak wool is 66% more breathable and 40% warmer than merino, …

These are the warmest men’s sweaters I’ve found for 2019:

These are the warmest base layers I’ve found for 2019: