Wilson Combat Extractor Upgrade Kit 5.56 NATO/300 BLK/300 HAM'R. These thoroughly tested parts are produced of the finest materials and machined to close tolerances. Features of Wilson Combat Extractor Upgrade Kit Extra Power Chrome Silicon Spring Lasts Many Times Longer Than Standard Spring. Dual O-rings Provide Enhanced Extractor Tension for Heavy .308 5.56Based Calibers. Better Than Standard Extractor-Fully Hardened and Machined From Billet Steel for Enhanced Extraction. Package Contents: Wilson Combat Extractor Upgrade Kit Wilson Combat TR-EXT556: Extractor Upgrade Kit 5.56 NATO/300 BLK/300 HAM'R