The Little Giant ACS-4 In-Line Condensate Drain Overflow Shut-off Switch is a simple and easy to use device that can be used to shut off the flow of condensate from an in-line condensate drain. This switch is perfect for use in applications where the flow of condensate is a safety hazard or where the flow of condensate is excessive. The Little Giant ACS-4 In-Line Condensate Drain Overflow Shut-off Switch is a simple and easy to use device that can be used to shut off the flow of condensate from an in-line condensate drain. This switch is perfect for use in applications where the flow of condensate is a safety hazard or where the flow of condensate is excessive.