The Extech SDL150 records data in Excel format on an SD card. It has a dual display with backlight to show the oxygen concentration and temperature. It measures the gel oxygen from 0 mg/l to 20.0 mg/l and from 0 % to 100.0 % oxygen and the temperature from 0 °C to 50 °C (32 to 122 °F). Incl. automatic temperature compensation from 0 °C to 50 °C üvia a temperature sensor integrated in a polarographic oxygen probe. Offset button for zero function for relative measurements. The SDL150 stores 99 readings manually and 20 million readings on a 2G SD card. User programmable sampling rate. It has an integrated PC interface, min/max and data hold functions as well as an automatic switch-off function.