... 2.compressive resistance 3.flexual resistance 4.good quality and low price 5.long using longevity Alumina ceramic discs ... modulatory valve,conversion valve,modulatory valve of surfing and massage bathtub,LPG valves and so on Good hermetical property,compressive resistance, ... temperature modulatory valve,conversion valve,modulatory valve of surf and massage bathtub,LPG valves1, Flatness≤0.03μm,roughness ...