20000-360005 water flow switch used in many Heat Pumps and other appliances. Semi-universal fit. Used by Hayward, Astralpool, Sunlover, Oasis, Zodiac, Phnix, SpaNet and many others.
Note that each heat pump manufacturer has different plugs, so you may need to cut and join the two wires. Polarity does not matter.
Most fail due to water balance issues or bromine.
20000-360005 / HPX20000-360005 / 040060600000