The SPI 20A601 is a normally open, control duty, mechanical float switch. Normally open (Pump Down) means that the float will be OFF in the normal (hanging) position and ON in the upright (floating) position. Control duty refers to how many amps the float can handle. Control duty floats are designed to be used on high water alarms. They do not have the amp rating required to turn on a pump but they have the amp rating to turn on an alarm.