Have you ever soldered a smd LED on a PCB only to realize later that the polarity is wrong or the LED is simply damaged. It is quite frustrating and painful to remedy the damage. This little LED tester is designed to prevent just that. You do not have to go to a great length to figure out which end of the tiny LED is anode or cathode. You simply pick up the LED with a tweezer and place it on the two parallel strip. One end of the LED on one strip and the other end on another strip. If the LED is lit then by looking at the symbol at the bottom of the strip you know which end of it is anode or cathode. You can also find the polarity of throughol through-hole LEDs. The size of the board is: 32x40mm. This tester requires a CR2450 coin battery and it is not included. This little device can be used to test smd LEDs of variaous sizes from 201 to 1206 and larger ones. Board size: 32x40mm