Reliable sealing and anti-aging. Good helper heater, gas valve and other maintenance. Made of positive materials, it can be used for an extended time. Replacing the previous one is a reputable choice. Type: Gas water heater accessories Colour: black Material: rubber Size: 54mm diameter Package Contents: one hundred x stress diaphragm Only the above package content, different products shouldn't included. Note: Light and varied exhibits may cause the colour of the object in the picture somewhat diverse from the genuine thing. The size allowed error is +/- 1-3cm.