Giant 22913A pressure actuated high flow unloader.  Ideal for multi-gun use. Repair kits available. 1/2"FPT Inlet, Outlet and Bypass 160 Fahrenheit Max Temp. 3500PSI Max 13GPM Max 2 - 1/4" FPT...

Multi-Gun Pressure Actuated Unloader by General Pump/PA 21 GPM Max 200°F Max Temperature Rating 1/2" Inlet 1/2" Outlet 1/2" Bypass 1/4" Gauge Port