Even warmer rides can benefit from the right baselayer. Bontrager's lightest weight baselayer fabric, B1, is a comfortable first layer of Profila Cool fabric enhanced with 37.5 technology that regulates the body’s relative humidity to maintain ideal core temperature, allowing greater on-bike performance. Comfortably fits under every jersey you own.

Key features:

- Profila Cool fabric powered by 37.5 active particle technology
- Conditions-appropriate, tuckable length
- Drop tail for a precise on-bike fit
- Fitted cut provides streamlined body fit for enhanced performance