4" 1st Check Assembly 300 / 400 (Flanged Body only)

Zurn Wilkins Backflow Prevention 350 (4 inch & 6 inch) - How to Repair

Zurn Wilkins Backflow Prevention Model 49 Butterfly Valve - How to Adjust Opening and Closing Stop

Zurn Wilkins Backflow Prevention Detector Assemblies - How it Works