The Wilkes & McLean Suppressor: is an "in line" device that reduces the noise of any hydraulic power unit. makes the unit quieter by absorbing the sound. reduces hydraulic pulsations that can cause pump wear and leakage at tube or pipe connections. can easily be installed on any existing power unit. Because of the small size of the unit, the most popular size is 8.25" long. comes in all pipe sizes; from 3/8" N.P.T. to 2" N.P.T., and all tube sizes; from .375" to 2.0". Flange connections are available in the larger sizes. The Suppressor is installed as close to the pump as possible.