A black silicon gasket in a concave shape. Used for mounting on side bars, side steps, light bars, or roof bars, for example. Suitable for 850405, 850406, 850407, and 850408, as well as the Dark Knight strobe light series with 6 LEDs (850403 & 850404). The concave shape of the gasket enables safe and stylish mounting on bars. Perfect for different vehicles such as ATVs, trailers, trucks, and construction machinery.