A check valve for use in a high-pressure pump is provided with a check valve seat having a frustoconical end region that engages a tapered surface provided on an outlet adaptor. A band pass filter unit separates an outgoing wave from an incoming wave. Data is also extrapolated from the full scan data. A bar code scanner system employing such housing can incorporate displays located on various sides of the housing andor key pads to facilitate a reading from the scanner at slanted angles. All credit payment data maintained in the credit data repository is maintained securely and will not be released without the consent of the consumer. These granules are suitable for use in a variety of applications.