Replacement O-rings for the Aqua Pro Steamer Valve. The kit includes citrus acid packet that should be used in the regular descaling of the tank of the Aqua Pro Steamer. The O-ring is made from rubber material and fits perfectly into the valve body making installation easy and quick. The citrus acid packet is safe and effective when used correctly, giving you assurance that your tank will remain scale-free. It also helps to extend the life of your steamer by helping prevent corrosion and the build-up of calcium which ultimately will cause the steamer to fail if not descaled regularly. With proper maintenance, this product will help ensure that your Aqua Pro Steamer operates at its best for years to come.