When it comes to winter base layers, 2XU understands that everyone carries their own preference in sleeve length. That's why it decided to create its flagship Engineered Women's Base Layer in a variety of sleeve lengths. So, if your allegiance lies in short sleeve iterations of base layers, you're in luck. For the construction of the Engineered base layer, 2XU relied on the venerable Meryl SKINLIFE fabric. This fabric was chosen for its hypoallergenic and bacteriostatic characteristics. By this, we mean that SKINLIFE has been engineered to maintain the ideal balance of bacteria on the skin. Yes, despite what the chronic hand-washers have to say, some bacteria is actually beneficial to our skin's health. Obviously, though, an exceedingly high level of bacteria creates its own set of problems. However, maintaining a natural presence, as SKINLIFE does, creates the ideal level of biological comfort. Additionally, within this balance, SKINLIFE prevents the growth of odor-causing bacteria. So, your base layer and body will remain free of stink, even after long, hot days in the saddle. Just as importantly, though, this material will regulate both your body temperature and the resulting moisture of long winter hours in the saddle. Or, in other words, you'll remain dry throughout the day. And to ensure that you won't ever run the risk of overheating, 2XU also incorporated laser-cut point of ventilation along the sides and chest of the torso -- natural evacuation points for excess core heat. As for the fit, you'll find that 2XU cut this base layer to the natural contours of the body. This way, the base layer fits easily under either a jersey or jacket, and it won't move against the skin throughout the motions of cycling. The 2XU Engineered Women's Base Layer is available in the sizes X-Small/Small and Medium/Large and in the colors Glass Blue and Violet Varnish.