Product Instructions for use: Connect the power supply and equipment, the measuring temperature is displayed. Press the SET button, press + or - to set the temperature, long press + or - to quickly increase or decrease. Press SET to confirm the setting and return, controller automatically performs the relay ON or OFF. The thermostat output is 10A relay, a of high-power loads. LED Indicator: LED off indicates the relay off; Lighting, indicates the relay is closed. Material: Metal+ABS Color as shown Digital LED tubes: LL indicates sensor open, indicates overrange, the relay will be forcibly disconnected; --- indicates high temperature alarm. Long press the SET button to enter the main settings. Press + or - to switching between P0-P6. Then long press SET or 10 seconds without keystrokes to confirm the setting and return. Specifications: Model: W1209 with case Dimensions: 48.5 x 40 mm Temperature control mode: ON or OFF Temperature range: -50 - 110 degree centigrade Resolution: when temperature is 0.1 degree, the resolution is -9.9 - 99.9, other temperature segment is 1 degree. Control accuracy: 0.1 degree Hysteresis accuracy: 0.1 degree Refresh rate: 0.5 s High temperature protection 0 - 110 degree centigrade Supply voltage: DC 12V Static current: less than 35MA, attract current less than 65MA Output voltage: DC 12V Output power: 20A relay Measurement input: NTC, 10K 0.5 percent waterproof sensor Requirements: -10 - 60 degree centigrade, humidity: 20 - 85 percent Package Contents: 4 x W1209 12V DC digital temperature controller boards with case Only the above package content, other are not included. Note: Light reflection and different displays may cause the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.