Part Number: 501001 402011 500407. Package Includes: as images show, 1set O-ring Rebuild Kit, 402011 Cylinder Seal 1pcs, 501001 Cap Gasket 1pcs, 500407 Spring 1pcs. These parts install quickly to make your nailer work like new again. A brand-new, unused, unopened, undamaged item in its original packaging.