This is the
Yokomo YD-2 Aluminum Front Upper L Arm Kit (Red) YOKY2-R08FUIA
The Yokomo YD-2 YD-2 Aluminum Front Upper L Arm Kit is a precision machined option, anodized red to match the red version of the YD-2. The design allows adjustment of the caster angle within a range of 7mm back and forth using the included spacers, and it is possible to increase the adjustment range and set the caster angle less than the standard settings. Although it is made of highly rigid aluminum, it is made as light as possible by making it an I-arm shape.
NOTE: These require the use of a D-155 series upper I arm rod end adapter (YOKD-155).