Heavy Duty, Corrosion and UV Resistant PVC Construction. The K-Rain® ProSeries 150 Valves offer the irrigation professional a wide array of features and benefits. "•Heavy Duty, Corrosion and UV Resistant PVC Construction – Increases the life of the valve. •Manual External Bleed Screw – Provides for manual operation in system start up. •Manual Internal Bleed through Solenoid – Provides for manual operation without discharging water outside the valve. •Captured Plunger – Allows for the solenoid to be removed without losing the internal plunger. •Flow Control Option – Allows for precise flow adjustment. •External Bleed Screw with Removable Metering Pin – Allows for easy cleaning of the metering pin without disassembling the valve"