The Waters™ Performance Maintenance Kit for the ACQUITY QDa Standard (KAD serial numbers) contains all the Waters Quality Parts™ necessary to keep your instrument operating at peak performance on an annual basis. The Waters™ Performance Maintenance Kit includes the following parts: seals and gaskets, calibration pin, pinch valve, aperture disk assembly, air filters. The kit does not contain a Probe Assembly, but it is highly recommended that to main peak performance, the appropriate Probe assembly is also ordered/replaced during Performance Maintenance. In addition, depending on the hours of operation, a Diaphragm Pump Service kit may also be required.