Xylem Bell & Gossett 189139 Bonnet & Retainer Assembly is a replacement valve component designed to restore the performance of compatible hydronic HVAC systems. It works by securely housing and supporting internal valve components, helping maintain proper sealing, pressure control, and smooth valve operation during system use. This assembly is commonly used in Bell & Gossett valves fo... https://www.partshnc.com/189139-xylem-bell-gossett-bonnet-retainer-v01372-indv