The R1 Concepts drilled-and-slotted black brake rotor is cataloged as a replacement rear-left rotor for a Workhorse medium-duty series listed in the source. Described as drilled & slotted with a black finish, it serves as a serviceable rotor for the rear brake assembly. Fitment is explicit: for the listed Workhorse series from 2006–2012 in the rear-left position, provided to align with factory mounting.
R1 06-12 Workhorse 000Lb Gvw) Rear Left Drilled & Slotted Black Brake Rotor