Few things are nicer to have along on any outdoor adventure than a fine wool sweater. Slip it on and you’re surrounded by warmth—perfect for curling up with a good book or while enjoying an evening’s gathering by the fire. To find the right sweater, however, you’ll need to wade through wool types, sizing, collar styles, more. Here are three things to consider before you buy your next one.

Collar Styles

Best Wools for Warmth

While most of us associate wool with sheep, wool is a generic term for any of the hair that is shorn from sheep, goats, or similar animals that can be spun into yarn for making cloth. Depending on the animal it comes from, wool can have a variety of properties.

Merino wool comes from sheep and is the most popular (and affordable) of the wool sweater materials. It’s rugged, warm, and will last for years provided it’s kept clean and packed in mothballs during the off-season. This is what typical fisherman’s sweaters are made from.

Cashmere is the softest of the wool sweater materials and can be eight-times warmer than sheep’s wool. It comes from the under hairs of the cashmere goat. The finest quality cashmere comes from China. It fetches high prices because the hairs are extremely thin and long, so they retain heat better. Fine hairs are also what produces that luxurious softness. Cashmere from Afghanistan and Iran has thicker hairs, so it’s not as soft and it tends to pill more. Look for cashmere sweaters with the highest “ply.” The higher the ply, the better the sweater will be.

Alpaca is the way to go if you’re allergic to wool. The Alpaca is a South American camel subspecies—similar to a llama, but a smaller species unto itself. It’s hair is prized for making sweaters because it has microscopic air pockets in its fibers that trap warmth—which is why it is the model for today’s modern microfibers. It does not contain lanolin and its hypo-allergenic, which makes it the perfect choice for those who may be allergic to sheep’s wool or cashmere. And because it’s 7% warmer than cashmere, Alpaca is the warmest sweater material.