Upper Parts Kit (UPK) for GLOCK 17 - Gen 5. These are great for completing your custom slide. Includes Firing Pin Spring and Pin Spacer Sleeve, Spring Cups, Firing Pin Safety Nitride and Spring, Extractor Depressor Plunger Nitride and Spring, Spring Loaded Bearing, Firing Pin Channel Liner, Extractor, Slide Cover Plate, Upgraded ZP Stainless Steel Recoil Spring Assembly. Features : Gen 5 Specific and Not Compatible with any other Gens All Parts are from US Manufacturer Parts are Made to the Highest Tolerance to the Original Specification ZP Stainless Steel Recoil Spring Assembly-OEM Spring Weight Fits GLOCK Gen5 17 and 34 GLOCK is a registered trademark of GLOCK Inc. 3CR Tactical is not affiliated with, endorsed by, or sponsored by GLOCK Inc. Any reference to GLOCK products is for identification and compatibility purposes only.