A rear suspension structure for large vehicles increases durability of a bump stopper and an air spring, thus markedly enhancing the riding comfort and handling ability of a vehicle. The controller is configured to produce a variable switching frequency depending on a load current. The device may also include first thermal vias extending from the mounting area to at least an interior of the substrate. The stand is capable of supporting the lighting device chassis. A lens structure having a first desired lens surface and a second desired lens surface is formed in the substrate’s recess.