The BN-LINK Digital Heat Mat Thermostat Controller allows gardeners to select and maintain optimum; Rooting temperatures for faster seeding or cutting growth. It is compatible with many other heat mats. It works great for controlling plant or pet heat mat temperature. Programming: 1. To display in Celsius, Please Press and Hold "DOWN" button for 3 seconds. Press and Hold "UP" button for 3 seconds to display temperature in Fahrenheit. 2. To adjust the temperature setting, Press and Hold "SET" button for 3 seconds to enter the temperature selection mode. Press the " UP" or "DOWN" button to adjust the temperature that you want to set. Then Press "SET" button again. So the setting temperature is done. Press "SET" button to display the preset temperature. When the unit is plugged into an electrical outlet, the "POWER" LED becomes lit, the heat on only when the "HEATING" LED is lighted. When the preset temperature is reached, the "HEATING" LED will turn off and there is no power to the heat mat. ATTENTION: If the thermostat remains "ON" ( delivering power to the heat mat) for more than 5 consecutive hours, it indicates the desired temperature is not being reached. To achieve higher temperature the Mat may need to be placed on a more insulated surface. Covering the seedling tray with a humidity dome will also help heat retention. Do not Immerse controller or probe into water. Do not exceed a total of 1000 watts of heating devices plugged into thermostat.