This kit from DoubleStar includes everything you need to completely rebuild your AR-15 bolt. It's great to keep around as spare parts incase something breaks, or proactively change after every 5000 rounds to ensure that your gun runs like new.

Specifications and Features:
DoubleStar AR-15 Bolt Rebuild Kit AR790
Extractor
Extractor Spring
Pad
Extractor Pin
3 Bolt gas rings
O-Ring
Steel
Matte Black