DoubleStar Extractor Upgrade Kit Black. Extractor O ring goes around external spring and bumper pad providing more forward pressure on the extractor. More pressure give the extractor more strength Specifications for DoubleStar Extractor Upgrade Kit: Manufacturer: DoubleStar Color: Black Fabric/Material: Steel/ Rubber/ Plastic Gun Model: AR-15 Weight: 2 oz Features of Doublestar Extractor Upgrade Kit Consists of:O ring extractor spring and extractor pad Package Contents: Doublestar Extractor Upgrade Kit What firearm models does the manufacturer say DoubleStar Extractor Upgrade Kit is compatible with? The manufacturer suggests that DoubleStar Extractor Upgrade Kit is compatible with AR-15DoubleStar AR125: Extractor Upgrade Kit Black