Kent what you have found is this.
15Amp Potted Water Pump Controller
The MONOPLEX Water Pump Controller is designed to operate as a "low side", remote switch in 12 volt DC systems. As it's name implies, it was designed to control the domestic water pump. It's use, however, is not limited to that. It can also be used to control a variety of other loads such as lighting, other pumps, fans, etc., when it is convenient to switch the ground.