BCG Rebuild/Maintenance Kit for AR15 M4 M16 5.56/.223 Includes:

Firing Pin, Chrome plated or Electroless Nickel
Firing Pin Retaining Pin
Cam Pin, Black Oxide
Gas Key, black Nitride
Gas Key Screws
3 Gas Rings
Ejector
Ejector Roll Pin
Ejector Spring
Extractor
Extractor Roll Pin
Extractor Spring w/Plunger Insert
Extractor O-Ring

All Parts Made in the USA

Fastener screws should be torqued to 35-40 in-lbs, and staked in. 
Screws that are not staked into place will loosen during firing and damage your firearm.