RectorSeal® Safe-T-Switch SS3™ detects rising water in A/C condensate drain pans and interrupts the thermostat circuit to shut off the unit before overflows and flooding occur. The Model SS3 is designed to install in auxiliary (safety) drain pans. The included stainless steel clip snaps easily in place on most pan rims and holds firmly. Compact footprint fits well in tight spaces. Approved for use as a substitute for auxilliary condensate drains in jurisdictions where the International Mechanical Code applies.