The SL704 data logger measures temperature, pressure and relative humidity. As standard, it is supplied with internal temperature and pressure sensors and a slot is available for an optional, relative humidity sensor (SL-RH002). It is also possible to use the external temperature and relative humidity sensor (SL-EH020). The SL704 can be used standalone or connected to pressure lines using the quick release pressure connector and a 1/4' hose. There are 4 measuring ranges available with gauge or absolute referencing. As with all of the SL700 series data loggers, the data logger is in a Noryl enclosure, battery powered for up to 10 years and has 12 bit resolution. There are also 2 memory options 32K storing 21,500 readings and 128K storing 87,000 readings.