The Oakton Instruments temperature probes are for units that have an electrode without a built-in temperature sensor and you want to take readings with Automatic Temperature Compensation (ATC). Separate temperature probes offer faster temperature response and lower pH electrode replacement cost. Temperature probes must be compatible with individual meter models. As such it is necessary to order these probes by selecting the type of meter with which they will be used. Oakton #: WD-35613-05