The SSSL is a stand-alone unit which uses two pressure transmitters and is able to measure process pressure, depth, and temperature. The depth measurement enables the pressure to be corrected for depth. The unit is powered by internal batteries and displays the parameters measured on a large display with clear characters on a high contrast back-reflective e-paper display. This display retains its last reading indefinitely so uses very little power. The system has a large internal memory allowing many readings to be recorded. The setup and download of the gauge are menu driven from a bespoke app running on a tablet.