Next-generation performance and ease of use makes the Rule 500 GPH Automatic Electronic Sensing Bilge Pump the obvious choice for better boating. This automatic bilge pump turns on every 2-1/2 minutes for about one second to sense water. If it detects water, the pump will sense resistance and continue to run until it senses no more water. The Rule 500 GPH Automatic Electronic Sensing Bilge Pump will then resume checking for water every 2-1/2 minutes, keeping water in check between 1/8 3/8. Perfect for conserving power, and unlike ordinary bilge pumps, this electronic bilge pump needs no float switch. Plus, it grants best of classic bilge pump performance: submersible; ignition-protected; a high-efficiency, low-amp motor; stainless steel shaft; and back flow preventer. As the smallest automatic pump on the market, this Rule bilge pump brings the biggest value and performance in its class. Cancer and Reproductive Harm- www.P65Warnings.ca.gov. Type: Bilge Pumps.