This is a siamp diaphragm washer, these are commonly used for siamp toilet valves to fir into the bottom and side siamp valves. This stops untightening or to spread the weight of a load out on a bolt. The smooth surface of the washer ensures that the nut is properly screwed on and that the nut is tightened with equal pressure on all sides to stop leaks. Features: Used for siamp toilet valves Stops nuts from untightening Equalizes the weight of a load out on the bolt Ensures that the nut is properly screwed on High quality and durable Specification: Finish: Black Colour: Black Brand: Oracstar Width: 29mm Length: 29mm Size: 29 x 29mm