Automatic Flapper Style Switch – Attaches to any SPX Johnson Pump Marine bilge pump through the T-slot, delivering full automatic bilge pumping action. For use with 6-, 12-, 24- and 32-volt systems. Electronic Float Switch – Compact mechanical switch activates pump at 2" water level, deactivates pump at 3/4" water level. Mercury-free electronics are encapsulated in high-impact plastic. False-start prevention. 12-volt. Handles up to 15 amps. Ultima Switch™ – No moving parts, no mercury, no exposed sensors and completely sealed. Activates at 2" water level and deactivates at 3/4" water level. Three-second delay prevents false starts. Handles pumps up to 20 amps at 12 or 24 volts.