Electronic Shut-Off (ESO) Switch with Wiring Harness UPGRADE KIT for Aquatec Booster Pumps Includes both the ESO and wiring harness to upgrade your current system that is using the TSO switch Shuts off water supply when pump shuts off and can be used with Aquatec CDP 6800 & 8800 pumps Connects using 1/4" quick-connect fittings. Simple to install and includes instructions with diagram To work correctly, the ESO must be used with the tank shutoff (TSO) switch