It is used on the way of the secondary side piping to keepthe cylinder in the middle position for a long time.Combining a double check block with a built-in pilot typedouble check valve and a two-position EXH centersolenoid valve will enable the cylinder to stop in themiddle or maintain its position for a long time.The combination with a two position single/double solenoidvalve will permit this block to be used for preventingthe dropping at the cylinder stroke end when the SUPresidual pressure is released.