By booting and reading the RAM Memory Slot Tester, it can indicate the error in the motherboard circuit for further repair The error can be detected by the LED light, indicating open circuit, short circuit, data line or address line Install the 3.3 v (CR2032) battery on the tester, motherboard does not need power on, on the tester's button If the LEDs all light up and the brightness are all the same, the signal is there is no problem Light out or weak light signals gives problem. You must refer to sign indication in addition to that LED light Size: 13.3 * 6 cm Material:PCB colour:green Package Contents: 1 * Tester card Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.