The 1U128B rotary dry air pumps unique bi-directional rotational design eliminates the need to stock multiple models and makes it impossible to install the wrong rotation pump on an engine. It may be operated either as a vacuum or a pressure pump. Its other unique features include an aluminum rotor and carbon-carbon composite vanes. This combination improves the vane wear rate and reduces susceptibility to premature failures, thereby improving reliability and extending service life. A no hassle, two-year warranty demonstrates our confidence in this pump.