The ¾” O-Ring Bonnet keeps pressure vacuum breaker assemblies in top shape. Designed specifically for ¾” 420 and 420XL Pressure Vacuum Breakers, this bonnet serves as the protective top cover that safeguards key internal components like the air inlet valve. Its corrosion-resistant bronze construction ensures long-lasting performance in both irrigation and plumbing systems, and features the added sealing protection of an O-ring for maximum security. maintaining pressure integrity and reliability.