This is a set of short replacement springs for one-piece tuning pipes. These small short springs connect the tuning pipe to the collector. These springs generally weaken over time due to the heat generated by the engine, so it's a good idea to replace these springs if they start to loosen (you should also replace the collector gasket at the same time). If the tuning pipe has a leak around the collector/pipe connection, this can cause unpredictable engine behavior.