This upgrade will help keep your AR-15 functioning reliably especially when dirty.
The Wolff Gunsprings Brand extra power extractor spring increases extractor tension and helps keep the extractor from slipping off the case head during extraction. This is especially useful on Short Barreled Rifles and suppressed guns and it's good insurance on 14.5" and longer barrel rifles as well. It is recommended to replace the extractor spring approximately every 5000 rounds to ensure proper function.
This extra power spring is so strong that the Mil-Spec Viton O-ring will probably not be needed, but it is included.