This is a set of replacement short springs for one piece tuned pipes. These are the small short springs that attach the tuned pipe to the manifold. These springs will generally get weaker over time due to the amount of heat generated by the engine, so it is a good idea to replace these springs if they become loose (you should also replace the manifold gasket at the same time). If your tuned pipe is leaking around the manifold/pipe connection, it will make the engine behave erratically.