The Boekel Scientific line of Open Source, User Programmable pH, Conductivity, Dissolved Oxygen and Temperature measurement devices work just like conventional probes and transmitters but allow for additional functionality because the equipment is built around an Arduino compatible board. The UNO is an open source circuit board that allows easy user programming and experiment control. An External I/O connector allows the transmitter to connect to pumps or alarms while the USB drive included on the transmitter allows for downloadable data logging. A large color screen and user friendly probe calibrations make this unit easy to use. Each transmitter includes the specific probe identified below while additional probes are also available for purchase as an accessory, only one transmitter is needed to work with all of the probes below.