Hydraulic Double Pilot Operated Check Valve Kit for Double Acting Cylinder 3/8" BSP. SPECIFICATION: Max Pressure = 300 Bar Opening Pressure = 0.5 Bar Operating Temperature = -25°C to +80°C Body Material = Steel Zinc Plated Pilot Ratio = 1:4 to 1:4.5 APPLICATION: A Double Pilot Operated check valve is used to block the flow of oil out of the cylinder, which in turn locks the cylinder in place until it is supplied with pressure to release it.