This is a control board meant to control the defrosting function within various compatible models of refrigerator. This is a genuine OEM part that is sold by itself, without any other hardware. This control board communicates with various temperature sensors/thermistors to prevent excessive frost buildup on the evaporator coils and connects directly within the cold control housing of your refrigerator. If you notice excessive frost or ice buildup, or the opposite in abnormally warmer temperatures within your refrigerator, it would be worth inspecting this board. You can also test this control board for continuity with a multimeter if you suspect it has failed from electrical problems. You will need a screwdriver to gain access to the housing the control board is kept in, in order for you to remove it. To replace it, disconnect your fridge from its wall outlet and unscrew the securing hardware from the housing with the control board. Remove any wire harnesses or cables connected to the control board and now you can install the new one or test the old one. Then simply reassemble the housing.