The Orion 520Aplus is loaded with advanced pH measurement features. It offers selectable ROSS Resolution to 0.001 pH units, choice of a three point autocalibration (built-in Auto-Buffer-Recognition of 5 buffers) or manual calibration, easy-to-understand user prompting and RS232 interface for connection to optional Orion Model 900A printer or your computer.

This product is discontinued, The new Orion Star Series equivalent is: Orion 3 Star