Ridex 251T0104 trailing arm / suspension arm bush for BMW X3 F25 and X4 F26, rear axle upper inner position (both sides). Rubber-metal mount construction with 14 mm inner diameter, 47 mm outer diameter, 55 mm height. Isolates rear suspension vibrations from the chassis and controls trailing arm articulation under cornering and braking loads. Direct OEM-equivalent replacement across multiple BMW and ALPINA applications. Supplied new in RIDEX quality.