Discontinued. Replaced by DOH-10.The DOH-SD1 is innovative and easy to operate. What sets the DOH-SD1 apart from other dissolved oxygen meters is that it incorporates a real-time SD card data logger. The DOH-SD1 measures dissolved oxygen and has adjustments for altitude and salt. Download data from the SD card into an Excel spreadsheet. This allows the user to do further data or graphical analysis without special software. The DOH-SD1 has a wide variety of applications from water conditioning, aquariums, and fish hatcheries to food processing, educational and other laboratories.