Designed with one simple brief: create the warmest, most comfortable, quickest-drying, and best-designed winter base layer available. The Basez Extreme surpasses its predecessor, the award-winning Basez2, offering a whole new level of warmth and protection for the coldest conditions. Advanced Insulation: Polypropylene yarn traps warm air against your skin, maintaining optimal temperature during intense activity. Seamless Construction: Engineered for maximum comfort, with inside weaves and waffles that actively pull moisture away to keep you dry. Wind-Stopper Technology: A breathable membrane across the chest provides a barrier against cold winds, keeping warmth locked in. Tested in Extreme Conditions: After four winters of testing in the UK, Alps, and Pyrenees, we’re confident the Basez Extreme outperforms multiple base layers, offering superior warmth and protection. Ergonomic Fit: Long arms, a dropped rear, short front, and high neck design provide a close, unrestricted fit that works perfectly with outer layers. Sizing Please note that the Basez Extreme is designed for cycling, so it has a close fit that’s most comfortable when you're in a cycling position. When worn correctly (if it’s the right size), it should feel snug around the shoulders but not restrictive. A snug fit is ideal for cycling garments. If you plan to use it for skiing or other activities, you might want to "size up" for added comfort.