Our AR15 Extractor Spring Assembly is the same quality mil-spec unit we use in our industry-leading UltraBolts. Assembly includes: Extractor spring, insert buffer of the proper mil-spec material and durometer, and high-temperature silicone Viton® fluoroelastomer O-ring that meets MIL-R-83248. Get one to complete a bolt assembly or, because an extractor spring assembly is a wear item like the tires on your car, as a replacement during a regular weapon maintenance schedule. Made in the USA. Throw one, or more, in your cart when ordering other stuff and you're set.