This 9mm parts kit works with a ZEV slide to create a completely functional upper assembly including all internals, an extra firing pin spring and ZEV backplate. NOTE: Fits Gen 1- 4. Not Gen-5 compatible. *Due to a shortage, channel liners may ship as black instead of red. If you prefer to wait for red, please contact customer service for the current lead time. Included Components ZEV Striker ZEV Extractor Channel liner Striker sleeve Spring Cups Extractor Rod, Bearing ,and Spring Assembly ZEV Backplate ZEV Steel Firing Pin Safety and Spring 2 lbs striker spring 3 lbs striker spring