Drop-in replacement kit for factory extractor spring assembly helps ensure more positive, dependable extraction to improve the reliability of your rifle. Stiffer springs, plus an extra rubber doughnut that slips over the coil spring, increase extraction force to four times the factory rating. Helps reduce jams caused by weak spring pressure that allows the extractor to slip off the rim and leave a spent shell in the chamber. Especially effective in short-barreled rifles.