Product details:

Pump switching relay for 3 zones Contractor friendly, easy-to-follow PC board layout Features external indicator lights for instant diagnostic feedback 100% Factory tested, UL and CSA Approved Proudly made in the USA Taco SR503 Switching Relay combines clearly labeled PC board layoutwith advanced features that allow for total system customization. External indicator lights provide instant diagnostic feedback, making asnap of service calls or new installation start-ups. Taco SR503 switching relays are UL and CSA listed, use standard ice cube replaceable relays and are compatible with conventional andprogrammable thermostats.