Merino wool is the material shorn from Merino sheep. These sheep are sought after for their coats, which are said to produce the finest, softest wool available. This wool is often used for athletic garments, as it breathes and wicks better than most synthetic fabrics. The wool comes in different grades that are based on the strain of sheep and its associated climate setting.

There are two types of Merino sheep: horned rams and Poll Merinos. Poll Merinos have small stubs, or scurs, if they have any horns at all. Merino rams have long, spiraled horns. There are also many strains of these sheep, which depend on the area in which they are raised. The four basic strains are Peppin, South Australian, Saxon, and Spanish.

Merinos are extremely adaptable to variable temperatures; therefore, they can be found in many areas of the world. Even though Australia is the leading producer of Merino wool, New Zealand produces the highest quality of this soft wool. Merino wool is softer and more finely crimped than other wools. There are five basic wool grades: strong, medium, fine, super fine and ultra fine. The wool is measured by micrometers — the lower the measurement, the finer the fiber.

Fabric made from Merino wool is used in the production of high-end outdoor aerobic clothing. Contrary to popular belief, the wool is neither itchy nor overly hot. It provides some warmth, though one of its renowned elements is its wicking abilities — it draws sweat away from the skin and retains the moisture, though the clothing still feels dry to the touch. The athlete is then able to avoid hypothermia while wearing wool, as opposed to another material such as cotton.

Due to its uniquely thin fibers, this type of wool does not retain odors — bacteria cannot find a solid surface to grow on, thus making it anti-microbial, as well. It also is hypoallergenic, as is most wool. Merino wool fabric will shrink when washed or dried, but not much more than would a similar cotton garment. It can easily be stretched back to its original shape.

Merino wool can also be blended with possum fur or polyester, as well as cashmere and silk. When combined with the latter fabrics, the ultrafine wool makes for a smooth and soft garment. Popular merino wool garments include lightweight knits and base athletic layers, Merino wool sweaters, and socks. Buyers should be sure to check the garment tag, as some wool is recommended to be dry-cleaned or hand-washed.