It will be clear from the price alone that this isn't exactly a regular base layer - the X-Bionic Energy Accumulator Evo is a multi-award winning, super-high-tech product developed by scientists working with athletes such as the Norwegian national ski team. This collaboration has created a piece of clothing that effectively adjusts to the varying temperature of your body in order to warm you when you're cold and cool you when you're hot.
It also offers compression technology and features like 'expansion chambers' around the knees to keep them warm when bent, a newly conceptualized 'channelling' ventilation system. Flowing around the body, this system continuously carries away moisture and warmth and allows air to redistribute to body regions not normally accessible by fresh air circulation. The system also claims to be able to target insulation of individual body parts against ambient coldness to prevent overall chills in your body.
All of which is a remarkable amount of technology in a pair of long johns...
In use you might expect all the various ribs and panels of the pants to be noticeable at the very least, but the pants feel remarkably warm, soft and supportive - pretty much like any other more high-tech base layer really.
It's likely that much of the scientific jiggery-pokery they offer will be wasted on your average skier or boarder, and £100 is an awful lot to pay for your underwear. But if you practice your winter sports to a high level or compete seriously it's an investment that may well be worthwhile - after all, if X-Bionic is good enough for the Norwegian ski team it's probably good enough for the rest of us...
