Thin: Thin apparel is lightweight, low bulk, ultra breathable, and fast drying. Thin apparel is generally designed to aid in moisture control by moving perspiration away from the skin to the surface of the garment.
Medium: Medium-thick apparel usually has a greater stretch than thin apparel, but maintains many of the other qualities of thin apparel. For example, most medium-thick apparel is designed to pull moisture away from the skin to keep you cool and dry.
Thick: Thick apparel is designed to help maintain your core body temperature. It is generally less breathable than thinner apparel, but makes up for it in its added warmth.