Product no.: EU2004545 SCHMEISSER Multi Wire Spring Mfr Part: Sch203517-0280s4251366500352 Improves function and shooting performance in all AR15 models It causes less noise and extends the life of the buffer tube The multi-wire spring reduces recoil and provides a smoother and more reliable bolt movement movement, especially when using different ammunition Increases the reliability of the rifle through redundant, mutually supporting spring wires similar to the MG3