The Extech SDL500 records data on an SD card in Excel format. Measure relative humidity, temperature, dew point and wet bulb. Adjustable data sampling rate. Stores 99 readings manually and 20 million readings on a 2G SD card. Type K/J thermocouple input for high temperature measurements. Large dual LCD display with backlight. Functions for recording/recalling min, max, data memory and automatic switch-off.