The thinner undergarments are designed to be worn directly against the skin as a moisture wicking base layer. They work best when worn closest to the body, since the material keeps the body warm, while at the same time helping to transport perspiration. The thinnest undergarments are ideal at temperatures ranging from +10 °C (50 °F) down to -20 °C (-4 °F), depending on activity.
The garments will fit both men and women.
| MEASURES IN INCHES | XXS | XS | S | M | L | XL | XXL | XXXL | |
| Chest | 30-32″ | 32-35″ | 35-39″ | 39-42″ | 42-45″ | 45-48″ | 48-51″ | 51-54″ | |
| Waist | 23-26″ | 26-29″ | 29-32″ | 32-35″ | 35-39″ | 39-43″ | 43-47″ | 47-51″ | |
| Hips | 32-35″ | 35-39″ | 39-42″ | 42-45″ | 45-48″ | 48-51″ | 51-54″ | 54-57″ | |
| Inseam | 26-30″ | 27-31″ | 28-31″ | 29-32″ | 30-33″ | 31-34″ | 31-35″ | 32-35″ |