silicon ring 1) high quality and reasonable price 2) environmental friendly 3) nice design 4) ISO9001:2000 Silicon RingDescription:1) used between the inner tank and the vacuum tube to prevent water leaking from the tank and prevent the dust in the air gets into the tank to pollute the water in the tank as well2) thermostability, anticorrosion3) no smell, no toxin, no contaminations4) good ...