How to use: P0.Temperature Control Mode:when first use this product;if it is used to heating,please set H,if used to cooling,please set C P1.Return Difference Setting:long press SET key entering into internal setting,choose P1 seting;then press SET key to achieve return difference value setting P2:Temperature Calibration:this function is for temperature calibration.If detection temperature and actual temperature is different,then usrs can apply this function to calibrate P3:Delay Start:this function is for compressor cooling P4:Set High Temperature Alarm Value:when actual temperature is higher than this value,screen will flash and sound an alarm Restore Factory Settings: While power is on, press and hold the + - button for 3 seconds Note:Size for manual measurement, there may be a 0 to 2mm error, belongs to the normal phenomenon.