The Water Witch ® 217, 230, 101, 230-24, 101-24 submersible electronic bilge pump switches allow boat owners to forever rid themselves of the archaic outdated float switch. Instead of an unreliable and short-lived mechanical float switch, our electronic bilge switches have no moving parts and require no adjustments. This eliminates the chance of your battery dying or your pump burning out because of a jammed-on float switch. Temperature, humidity and electrical noise will not effect this switch, nor will it interfere with other electronics. It is mercury free, and not activated by oils & fuels, has built-in on/off delay to avoid false pump cycles