This is an optional XRAY XB2 Dirt Edition 23/29° Brass Front Lower Arm Mount.
Optional brass kick-up mount with integrated 23° and 29° kick-up angle. The brass arm mount adds weight to the front of the car and makes the car more stable and increases on-power steering. Must be used with #321211 Alu Front Lower Arm Mount 23°/29° Kick-Up Brace - 7075 T6