The piranha LED different from the general LED is that it has four legs, but as long as the positive and negative poles are connected to each other, they will light up. The method of determining the positive and negative poles is to place the piranha LED with a bevel at the upper right corner, the right two feet is the negative pole, and the left two feet are the positive pole. The best way is to use a digital multimeter to measure, hit the diode file, red and black negative will light up, determine the positive and negative poles can be connected.