If I want to buy a data logger what else should I buy?

For a thermocouple data logger, you need to buy the thermocouple sensor/probes.

For a external thermistor data logger, you need to buy the thermistor probes.

All data loggers need SiteView software to download the data and configure the logger for new logging session.

If you want to communicate with the logger via Ethernet or MODEM instead of USB port you need to buy other accessories. Please refer to Accessories section of Products for details.