The Zipp 404 Firecrest Carbon Road Wheels are built with unidirectional fibers to increase vibration dampening without sacrificing stiffness. A visco elastic material is inserted between carbon laminate in the rim to further reduce road vibration. This also provides both vertical and lateral compliance. Woven carbon is used at the spoke holes to ensure strength at the rim's load bearing points. The rim is made with Zipp's Aerodynamic Boundary Layer Control ABLC, the little dimples that set it apart visually as well as aerodynamically from competitors. It forces the laminar boundary layer toward the front of the wheel to become more turbulent, allowing the air to remain attached to the rim longer, and while this seems like a lot of counterintuitive tech speak, it means that the ZIpp 404 Firecrest wheels are faster in a wider range of conditions including yaw angles of up to 20 degrees.