Chrome Silicon AK -47 Semi-Automatic Spring Kit. This kit contains the following: Main Recoil Spring, Hammer Spring, Extractor Spring, Semi Auto Retainer Spring, Sear Spring. These are all new production and have been tested to ensure flawless functioning. Ensure your weapon is functioning at its best or get a back up set. Chrome Silicon is a premium spring material rated at over three times the life of a regular music wire spring material.