In the design of the MPB metal switch double-color lamp, a double-chip LED lamp is used. This type of LED lamp has a small size and high brightness. After the astigmatism of the light-conducting plastic parts, the color is uniform, and no light-emitting area is generated. The condition of the shadow, and then achieve the beautiful effect; and due to the dual-chip LED light color switching, it is necessary to use the reverse change of the positive and negative current conduction direction to achieve, usually in the design of the board end, it is necessary to design different power supply circuits, in MPB16L The product has this function buried in the switch, which can directly switch the color of the light, but in the MPB19~25 product series, if the board terminal is not used to complete the current direction exchange to achieve two-color switching, the design of double POLE can be used to achieve this. (But at the expense of the ability to control both sets of circuits).