The Walchem WDB300-1NN controller is now obsolete and has been replaced by the WDB400-1NNU controller which now has integrated USB datalogging and software upgrade capability. Otherwise, both the WDB300-1NN and the WDB400-1NNU have the same specifications with 120 VAC, prewired, no 4-20 mA output, no electrodes, integrated datalogging and config file import/export via USB flash stick.
Please click here to view and/or purchase the new replacement controller and to view literature.