The Potter VSR-4 VSR Series Vane Type Waterflow Alarm Switch is designed for 4" nominal pipe size systems and assembled in the USA, ensuring quality and reliability. It features a 0-90 second field-replaceable time delay retard for customizable performance. The easily visible retard time delay adjustment knob allows for simple and precise settings. Equipped with two SPDT (form C) contacts and a weatherproof build, it guarantees durability in various conditions. Clear wire terminal designations further simplify installation. Upgrade your system with this dependable waterflow alarm switch today!