The Strike Industries AR PDW 9mm Buffer enables proper configuration of the SI PDW Stock, SI PDW Stabilizer or pistol length receiver extension to work on most AR-15 9mm direct blowback systems on the market. Made from steel, the buffer housing holds two (x2) tungsten weights and gives you a total of 4.6 ounces. The buffer pad on the buffer housing is made out of a resilient NBR rubber material to absorb the 9mm direct blowback impact. This 9mm buffer includes a flat wire buffer spring that is fine-tuned specifically for the buffer in SI PDW systems and most pistol length buffer tubes, making it simple and complete. Flat wire spring design packs more energy than traditional round wire springs, giving it increased bolt power. Known for efficiency since the flat wire spring is able to store a larger amount of energy in a smaller space. The Strike Industries AR PDW 9mm Buffer gives you the option to use the SI PDW Stock/Stabilizer or a pistol length receiver extension reliably and accurately on an AR 9mm build.