This is a pair of rear caliper mounting bolts, 10.9 hardness, M12 X1.5 X 35mm with flange & Loctite.
Mercedes recommends ALWAYS replacing any hardware used on brakes or suspension.
These bolts fit select models of the 2008 - 2020 Mercedes C, CL, CLS, E, GL, GLE, GLS, ML, R, SLC, SLK models so PLEASE see the application fitment tables to confirm fit.